World!Of
Numbers

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PREVIEW ZONE

May 23, 2024 230
  Searching for sums of five fifthpowers.  
  pdg
Jan 31, 2024 229
  Detecting patterns in sum of the first n palindromes.  
  Tony Sand
Oct 13, 2023 228
  Spotting palindromes 78087 and 672276  
  in the formula for indexing Fibonacci numbers.  
  pdg
Oct 9, 2023 227
  Bringing palindrome 10901 into an interesting state  
  pdg
Oct 8, 2023 226
  Every positive integer can be expressed as the sum of maximum three palindromes  
  pdg
Jun 4, 2023 225
  Building a relationship between the natural numbers and the ninedigitals  
  using the surjective function described in WONplate 224  
  pdg
May 20, 2023 224
  Prepending n digits d to k so that [d^^n][k] becomes a record delayed prime  
  Xinyao Chen
Nov 10, 2022 223
  Smallest multipliers to make a number palindromic in bases 2 to 12  
  Xinyao Chen
Oct 9, 2022 222
  Highlighting semiprime palindromes and their merit scores.  
  pdg
Sep 10, 2022 221
  Invitation to find prime factors of SUPP's or SUP's  
  Invitation to search for ever larger NSUP primes.  
  pdg
Jul 16, 2022 220
  Searching for a palindrome with various factor-lengths  
  representing my birthdate October 9, 1956  
  pdg
May 19, 2022 219
  Adding digits to n (beyond base 10) so that n becomes  
  a record delayed prime {or a FEP = First Encountered Prime}  
  Xinyao Chen
May 6, 2022 218
  Minimal primes in other bases  
  Xinyao Chen
May 1, 2022 217
  Operations with nine- & pandigital factors creating palindromes  
  Alexandru Petrescu
Mar 23, 2022 216
  Pandigital 1253098674 lies at the base of a palindromic curiosum  
  pdg
Mar 01, 2022 215
  Sequence & patterns with n and φ(n) both palindromes  
  Alexandru Petrescu
Jan 09, 2022 214
  Building sequences out of concatenated palindromes  
  pdg
Dec 14, 2021 213
  Exploring Mendeljev's palindromes  
  Lucas Rouchere
Dec 08, 2021 212
  Record palindromic substrings in the decimal expansion  
  of various types of numbers  
  pdg
Dec 05, 2021 211
  Ascending meta_ninedigital prime factors in the list  
  of palindromic squares and how to program them  
  pdg & Alexandru Petrescu
Oct 14, 2021 210
  Playing around with recreational examples of various types  
  like combinations using squares, factorials and other functions  
  Vinod Muleva
May 16, 2021 209
  Investigating prime multidigit subsequences in the list of 9!  
  ninedigital numbers and a programming challenge following it  
  Alexandru Dan Petrescu
May 12, 2021 208
  Langford's problem versus double pandigital numbers  
  Daniel Hardisky
Mar 28, 2021 207
  9583859 a curious Palindromic Prime  
  Petrescu & Roonguthai
Feb 02, 2020 206
  A palindromic date to remember !  
  Inder J. Taneja
Dec 10, 2020 205
  The superpermutation of 123 turns out to be the following  
  length_nine palindrome 123121321  
  Dr James Grime
May 10, 2018 204
  The discovery of new irregular non-palindromic and without  
  ending with zero square number reversals  
  Andres 'Tush' Molina
Aug 23, 2017 203
  A primorial way to search for (probable) primes  
  R. A. Bonham
Jul 02, 2017 202
  The rarity of sporadic square reversible numbers that are not  
  palindromic and without ending with zero  
  Andres 'Tush' Molina
Dec 23, 2016 201
  The mean merit of the borderprime gaps converges to 2  
  pdg
Oct 23, 2016 200
  Search for the smallest numbers that when appended by the same  
  amount of digits 1, 3, 7 and 9 generates primes in all four cases  
  Abhiram R. Devesh
May 16, 2016 199
  Missing solutions for the smallest palindrome k > n such that  
  k/n is a square  
  Pieter Post
Mar 21, 2016 198
  The sum of two numbers, their squares and their cubes  
  Pieter Post
Dec 06, 2015 197
  Adding 1's, 3's, 7's and 9's to n so that n becomes a record  
  delayed prime and more derived challenges along the way  
  pdg & partakers 
Oct 23, 2015 196
  Expressing the natural numbers as an absolute difference  
  between two powers  
  pdg
Jul 15, 2015 195
  Finding a pandigital as a substring in the decimal expansion of  
  that same pandigital raised to a power  
  pdg
Apr 20, 2015 194
  A new twist on Home Primes  
  Jeff Heleen
Feb 01, 2015 193
  Exploring nine- and pandigitals expressible as sums  
  of two squares  
  B.S. Rangaswamy
Jan 15, 2015 192
  n and n_reversed are square numbers whose roots may also  
  be [ pseudo-] reversible  
  Andres Molina
Jan 04, 2015 191
  n and its reverse are one less than a square number  
  Andres Molina
Nov 29, 2014 190
  OEIS Reference Table for primes of the form 10n ± d  
  and searching for some patterns  
  pdg
Jul 10, 2014 189
  Plea for interpreting ninedigitals with a leading zero as pandigitals  
  Heine Wanderlust
Jan 16, 2014 188
  Gathering prime factors of nine- and pandigitals and extracting  
  statistical information from the data  
  pdg & Alexandru Petrescu
Jan 02, 2014 187
  Expressing nine- or pandigitals as sums of powers of 2 and/or 3  
  pdg & B.S. Rangaswamy
Dec 17, 2013 186
  Saying goodbye to 2013 and welcoming 2014  
  anonymous & pdg
Sep 28, 2013 185
  Multiplying and dividing ninedigitals by 2  
  Mike Fairley
Jul 28, 2013 184
  Innovative Cashier  
  The topic began in WONplate 179 and continues here  
  B.S. Rangaswamy
Jan 28, 2013 183
  A selection of pandigital expressions found on the net  
  various partakers
Jan 13, 2013 182
  Gathering strictly pandigital probable primes (PRP's) of the form  
  ' ab^cdef +/- ghij ' and various other formats  
  pdg
Dec 03, 2012 181
  Pandigital PRP's of the form ' abcd! +/- efghij '  
  (a 4-digit factorial and a 6-digit displacement)  
  pdg
Nov 22, 2011 180
  A distinct palindrome becoming a product of two pandigitals  
  B.S. Rangaswamy
Feb 02, 2011 179
  All numbers above 23 are either Powers or Sums Of Powers  
  and a topic involving combining numbers with their reversals  
  B.S. Rangaswamy
May 08, 2009 178
  Searching for ever larger sporadic palindromes of the form  
  Ap + Bq (Sum Of Powers)  
  pdg & partakers
Mar 21, 2009 177
  A 42/42 palindromic/pandigital Bi-Forked Wheel  
  B.S. Rangaswamy
2009 176
  A Happy New Year (2009) to everyone !  
  Philippe Guglielmetti
Nov 24, 2008 175
  Multiplying Palindromes to arrive at a wheel of Pandigitals  
  Peter Kogel & B.S. Rangaswamy
Sep 15, 2008 174
  Hopping Numerals  
  B.S. Rangaswamy
Mar 20, 2008 173
  Blending palindromes and nine- & pandigitals using multiplication by 9  
  B.S. Rangaswamy
Jun 17, 2007 172
  A pandigital puzzle from professor Seppo Mustonen,  
  author of Survo MM
  Kimmo Vehkalahti
May 21, 2007 171
  A random walk around the powers of ten  
  Milton L. Brown
Feb 25, 2007 170
  A ninedigital enigma  
  Michael Bergman
Nov 11, 2006 169
  Two nice consecutive primes  
  Farideh Firoozbakht
Sep 04, 2006 168
  Pandigital Curios  
  Carlos Rivera
Nov 12, 2005 167
  “Wonders of Numerals” written by   
  B.S. Rangaswamy
Oct 15, 2005 166
  The Beast's real mark devalued to 616  
  Enoch Haga
May 30, 2005 165
  An amazing Palindromic Circle  
  Giovanni Resta
Mar 19, 2005 164
  Equations concerning Pythagorean Theorem and  
  Fermat's Last Theorem  
  Bob Hein
Jan 23, 2005 163
  List of palindromic areas of primitive Pythagorean triangles  
  Zakir Seidov
Jan 16, 2005 162
  Sumas Palindromizadas con Factores de Corrección  
  Números Naturales del 1 al 100  
  Hugo Sánchez
Jan 10, 2005 161
  Nearest (probable) primes bordering powers of ten situated at equal distances  
  pdg
Oct 18, 2004 160
  Two Prime Numbers starting from 18 and 19  
  Farideh Firoozbakth
Sep 20, 2004 159
  Numbers and their reversals have a difference divisible by 9  
  and a sum divisible by 11 and a palindromic endresult  
  Andrei Cucuianu
Sep 02, 2004 158
  Extracting Palindromes from Pi (e.g. 7446447 & 110000011)  
  Klaas Craye
Aug 15, 2004 157
  Find larger and larger palindromic primes  
  dividing numbers of the form k.bn ± 1 (k > 1)  
  pdg & Jean Claude Rosa
Aug 07, 2004 156
  A simple procedure to arrive at palindromes  
  Paul Oliverio
Feb 15, 2004 155
  ABBA primes  
  Patrick De Geest
Dec 01, 2003 154
  December 1, 2003, not merely a date...  
  46664, not merely a palindrome...  
  pdg & David Broadhurst
Nov 03, 2003 153
  Patrones Palindromicos con Multiples Operaciones Aritmeticas  
  Hugo Sanchez
Oct 13, 2003 152
  Tautonymic numbers  
  pdg & partakers
Sep 01, 2003 151
  Recurring last digit multiplication numbers  
  Allan Jenks
Mar 04, 2003 150
  Top3000+ palindromic primes with prime digits  
  pdg & many prime provers
Jul 27, 2003 149
  Expressions with a palindromic look  
  Don Mcdonald
May 04, 2003 148
  Concatenate two (almost) neighbouring primes  
  so that you end up with a square  
  pdg & partakers
Apr 27, 2003 147
  181, 313 & 545 are the only Plateau and Depression Primes  
  equal to the sum of the squares of two consecutive integers  
  Jean Claude Rosa
Feb 16, 2003 146
  A threefold (probable) prime search  
  pdg
Dec 29, 2002 145
  Palindromic sums of powers of (at least two) consecutive numbers  
  pdg
Nov 15, 2002 144
  A free forum for Gigantic Primes  
  pdg
Nov 12, 2002 143
  Palindromic Primes stretching out until...  
  Jeff Heleen
Nov 06, 2002 142
  Double Cross Palindromes  
  Enoch Haga
Oct 08, 2002 141
  Literary Primes  
  Enoch Haga
Oct 06, 2002 140
  8778 a curious Palindromic Triangular  
  Jean Claude Rosa
Sep 06, 2002 139
  1|9|9|1 a vertical palindrome  
  Enoch Haga
Jul 22, 2002 138
  An irrational palindromic number  
  John Prophet
Jul 21, 2002 137
  11 ways to arrange the ninedigits  
  Paul Gissing & Jean Claude Rosa
Jul 19, 2002 136
  Interesting pattern in reciprocals  
  David Brickell
Jul 14, 2002 135
  A very unique palindrome 549945  
  Terry Trotter
Jul 08, 2002 134
  JavaScript Palindrome tester  
  Hassan Elbekraoui
Jul 07, 2002 133
  Primes remaining prime when its digits are intertwined  
  with their SOD (Sum Of Digits) strings  
  pdg & Jean Claude Rosa
May 05, 2002 132
  Antimagic Squares using Primes with sums in Arithmetic Progression  
  Jean Claude Rosa
May 03, 2002 131
  Powers of Palindromes as products of integers and their reversals  
  Carlos Rivera
Apr 17, 2002 130
  Substrings in Primes of Composite length  
  pdg
Apr 01, 2002 129
  Magic Squares composed of only Palindromic Primes  
  Jean Claude Rosa
Mar 01, 2002 128
  Keithing to 2002... an exploration, a search for patterns  
  Terry Trotter
Feb 25, 2002 127
  Power of Patterns  
  Klaus Brockhaus
Feb 17, 2002 126
  An interesting tetradic prime  
  Harvey Dubner & David Broadhurst
Feb 11, 2002 125
  The smallest composites of length n that are  
  pseudoprime to base 2  
  pdg
Feb 03, 2002 124
  Find more palindromic pseudoprimes to base 2  
  pdg
Jan 22, 2002 123
  Bringing democracy into the Rabbit series  
  John McNamara
Jan 09, 2002 122
  Numbers equal to the sum of (at least two) consecutive integers  
  & numbers equal to the sum of (at least two) consecutive primes  
  pdg
Dec 20, 2001 121
  Various palindromic observations  
  To start with... welcome to palindromic WONplate 121 !  
  Enoch Haga
Nov 11, 2001 120
  Enoch Haga's new book (“Exploring Prime Numbers”) is out  
  A must for all prime number lovers  
  Enoch Haga
Nov 06, 2001 119
  Exploring Nine- & Pandigitals in other bases... your turn  
  pdg
Oct 22, 2001 118
  Have you ever... palindromes in the Golden String !  
  John McNamara
Oct 12, 2001 117
  Four in a row▪▪▪▪  Semiprimes !  
  pdg
Oct 09, 2001 116
  An ODD_DDO puzzle question 1 3 5 7 9  
  pdg & partakers
Oct 09, 2001 115
  How many palindromes can you find  
  that are the products of two pandigital numbers ?  
  pdg & partakers
Sep 24, 2001 114
  Palindromic quotients through pandigital divisions  
  (zerofree pandigital or ninedigital variation appended)  
  pdg & partakers
Sep 03, 2001 113
  A titanic prime expression using only palindromes  
  Jim Fougeron
Sep 02, 2001 112
  A magical blending of different concepts in a most beautiful pattern  
  Terry Trotter & pdg
Jul 16, 2001 111
  Analogical Reasoning and The Power of Patterns  
  Klaus Brockhaus & pdg
Jul 16, 2001 110
  A Pandigital Programming Challenge based on sequence A061604  
  Amarnath Murthy
Jul 16, 2001 109
  723121327 a peculiar palindromic prime  
  Carlos Rivera
Jul 16, 2001 108
  A palindrome story for 89  
  and a Fibonacci story for \( {1 \over 89} \)
  Terry Trotter
  Ir. Jos Heynderickx & Dr. Luc Gheysens
Jul 09, 2001 107
  Ninedigital 'Kordemsky' Divisions (complete list)  
  Preon
Jun 25, 2001 106
  29 extra Palindromic Patterns (Productos Palindrómicos)  
  Hugo Sánchez
Jun 17, 2001 105
  More Palindromic Sums of Twin Prime Pairs  
  Hans Havermann
Jun 16, 2001 104
  The Most Unpopular Palindrome must be... 404  
  pdg
Jun 03, 2001 103
  Polygonals with palindromic sides, rank and number  
  Jeff Heleen
May 28, 2001 102
  Palindromic Triangulars containing only 6's  
  Brian Wallace
May 20, 2001 101
  Intrinsic k-palindromes  
  Neil Sloane
May 20, 2001 100
  A Palindrome Question Can numbers  
  from 1 to k (in order) ever become palindromic ?  
  Maria Gerardina Bulanon
May 10, 2001 99
  Palindromic Primes in Arithmetic Progression  
  Harvey Dubner
no date, 2001 98
  Integer 6643 joins the World!Of Palindromes !  
  pdg
Apr 09, 2001 97
  How many palindromes can you find  
  that are the products of two ninedigital numbers ?  
  pdg & partakers
no date, 2001 96
  A follow-up from WONplate 36 and a new ninedigital puzzle  
  pdg & partakers
Mar 26, 2001 95
  A Ninedigital Divertimento  
  Janean Wilson
Mar 12, 2001 94
  A Puzzling Palindromic Sequence  
  Sonja Sharp
Mar 02, 2001 93
  Palindromic Patterns using Odd & Even Tiles  
  Dr. Wendy Klassen
Feb 26, 2001 92
  Palindromes in factorial base and base 10  
  pdg & Erich Friedman
Feb 22, 2001 91
  Primefree Palindrome Interval  
  pdg
Jan 25, 2001 90
  Two Palindromic Prime Records  
  Harvey Dubner
Jan 13, 2001 89
  Factorials and Binary Numbers  
  Kiwoo Song
Jan 13, 2001 88
  Counting palindromic patterns  
  Marks R. Nester
Jan 05, 2001 87
  A Palindromic & 'Sophie Germain' pair of magic 3x3 squares  
  Jaime Ayala
Jan 03, 2001 86
  Palindromic Prime Curios and Cubes  
  pdg
not dated 85
  Nine Digits Digressions  
  pdg & G. L. Honaker, Jr.
no date, 2000 84
  Palindromic Patterns  
  Hugo Sánchez
not dated 83
  Repdigits, or numbers with repeated digits  
  pdg
Mar 05, 2022 82
  Leisure time An addictive 4 X 4 shuffle board  
  pdg
not dated 81
  The palindrome Fifty Five or 55  
  pdg
not dated 80
  Some curious polygonals  
  pdg
Nov 07, 2000 79
  Some old and new discoveries about the Number of the Beast 666  
  pdg
Oct 03, 2000 78
  Sets of three composites in bi-directional  
  'Sum Of Prime Factors' progression/retrogression  
  pdg & Roberto Botrugno
Jun 14, 2000 77
  A Home Prime breakthrough  
  Paul Leyland
not dated 76
  Pi function for a special palindrome 𝜋(34543)  
  Chris K. Caldwell
not dated 75
  A webpage around palindromic heptagonals  
  pdg & Jeff Heleen
May 21, 2000 74
  Probability of finding palindromic squares and cubes  
  Mike Bennett
Apr 02, 2000 73
  The sum of the first 202 composite numbers is 27072  
  G. L. Honaker, Jr. & Jeff Heleen
Mar 08, 2007 72
  A combinatorial problem  
  Kanisher Caldwell & pdg
Feb 21, 2000 71
  Arranging all the base b representations of palindrome 31113  
  pdg
Dec 27, 1999 70
  Find more smallest Squares and Cubes whose digits  
  occur a same number of times  
  pdg & Jeff Heleen
not dated 69
  Palindromic sum of two consecutive primes  
  equal to the sum of their reversibles  
  Carlos Rivera & Jean Claude Rosa
not dated 68
  All the left-truncatable primes  
  Eric Weisstein
not dated 67
  An Interpalindromicum (19912002)  
  pdg
not dated 66
  Partitions of the Number of the Beast 666  
  pdg & partakers
not dated 65
  Inserting any digit d between adjacent digits of palprime 13331  
  never produces a new prime !  
  pdg
not dated 64
  An all palindromic diophantine equation intermezzo  
  pdg & Jean Claude Rosa
not dated 63
  Palindromes in the decimal expansion of  𝜋  
  pdg & partakers
Sep 10, 1999 62
  Four international palindrome occurrences  
  Syed Asadulla
Sep 16, 1999 61
  Two new gems about nine- and pandigitals !  
  G. L. Honaker, Jr.
Sep 12, 1999 60
  A prime free zone beginning with a palindrome  
  pdg
Aug 12, 1999 59
  One of a kind palindrome 21312  
  pdg
May 22, 1999 58
  Magic Squares with palindromic primes  
  Carlos Rivera & Jaime Ayala
May 25, 1999 57
  A square that is a palindrome in binary  
  pdg
Mar 1999 56
  An original puzzle involving primes  
  Enoch Haga
Feb 13, 1999 55
  A beautiful find this palindrome 3467643  
  Carlos Rivera
not dated 54
  Special operations leading towards palindromes  
  pdg & partakers
not dated 53
  A palindromic chain reaction  
  G. L. Honaker, Jr.
not dated 52
  My favourite palindrome 323323  
  pdg
not dated 51
  Some older site recommendations  
  pdg
not dated 50
  The On-Line Encyclopedia of Integer Sequences (OEIS)  
  Neil Sloane
not dated 49
  An entertaining palindromic puzzle  
  John Abreu
not dated 48
  Concatenating prime factors  
  pdg
not dated 47
  The most seksiest palindrome ever starting with 69  
  pdg
Dec 28, 1999 46
  More palindromic_free numbers  
  pdg
not dated 45
  Some beautiful patterns resulting in palindromes  
  pdg
not dated 44
  Finding non-palindromic numbers by multiplying with their reversals  
  pdg
not dated 43
  Operations with consecutive integers  
  pdg
not dated 42
  Excerpt from the book “The Moscow Puzzles” by   
  Boris A. Kordemsky
not dated 41
  Properties of the number 153  
  pdg & partakers
Jul 1997 40
  Sequences in the expansion of  𝜋  
  pdg
not dated 39
  Palindromes and Books  
  pdg
Apr 18, 2000 38
  Record Palindromic Triangulars  
  pdg
not dated 37
  Approximating 𝜋 with Palindromes  
  pdg & partakers
not dated 36
  Smallest multipliers to make a number palindromic  
  pdg & partakers
Feb 18, 2022 35
  Programming for palindromes  
  pdg
not dated 34
  89298 is a remarkable palindrome  
  pdg
not dated 33
  About Palindrome 888  
  pdg
not dated 32
  About Palindrome 22 and others as well  
  pdg
not dated 31
  1001, a Scheherazade palindrome !  
  pdg
not dated 30
  1001, 2002, 3003, ... featuring in Pascal's triangle  
  pdg
not dated 29
  A beautiful cryptic prime curio about palprimes 191 & 383  
  G. L. Honaker, Jr.
Jan 04, 2000 28
  Palindromic_free squares, cubes and primes  
  pdg
not dated 27
  Pattern excerpts from Mathematical Recreations books  
  pdg
not dated 26
  Palindromic Square 69696 = 2642  
  pdg & partakers
not dated 25
  323232323 is a smoothly undulating palindromic prime  
  pdg & partakers
not dated 24
  Magic Square with sum of rows equal to the root of a palindrome  
  pdg & partakers
May 15, 1998 23
  19291 and 124060421  
  constitute a remarkable palindromic duo  
  pdg
not dated 22
  About palindrome 1881  
  pdg
not dated 21
  Even the Number of the Beast is a palindrome !  
  pdg
not dated 20
  Palindromic Rheumatism  
  pdg
not dated 19
  music There is palindromic MUSIC in the air. Hear it out !  
  pdg
not dated 18
  ANS or the Alternative Number System  
  Bob Forslund
not dated 17
  Numbers whose product is the reversal  
  of the product of their reversals  
  Dr. Huen Y.K.
not dated 16
  A peculiar palindrome puzzle  
  M. Sedo Oh
Jun 18, 1999 15
  Basenumbers and binary looking palindromic powers  
  Felice Russo
Jun 27, 1999 14
  A Beastly Magic Sum  
  Jaime Ayala
not dated 13
  Palindromes and anagrams  
  pdg
Jul 12, 1998 11
  A palindromic soccer event  
  John Abreu
Dec 26, 1997 10
  Magic wishes for 1998  
  A.G. Pauwels
not dated  9 
  Magic Squares and Palindromes  
  pdg & Patrick Hamlyn
not dated  8 
  6n – 1 and 6n + 1  
  G. L. Honaker, Jr.
not dated  7 
  During the year 1999 this was the first paragraph of my homepage !  
  pdg
not dated  6 
  Palindromes in orbit  
  pdg
Jan 9, 2001  5 
  A retrospective view (5 years!) and  
  some palindromic primes for 1996  
  Jeffrey Heleen
Feb 9, 2003  4 
  The 196 Palindrome Quest  
  pdg & partakers
not dated  3 
  Articles about reversals and palindromes  
  Kevin Brown
not dated  2 
  What are Palindromes ?  
  pdg
Jan 27, 2022  1 
  Table of Contents  
  Patrick De Geest
A000001 Prime Curios! Prime Puzzle The Digits Project Richard Phillips
Wikipedia 1 Le Nombre 1 Numberland 1












































































































































































































 

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Patrick De Geest - Belgium - Short Bio - Some Pictures
E-mail address : pdg@worldofnumbers.com