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Palindromic Square 69696 = 2642 From “Keys to Infinity” by Clifford A. Pickover, Ed. Wiley 1995, page 159,160.69696 is a remarkable palindrome. Not only is it a palindromic square 2642 (see also WONplate 24), not only has it exactly 10 palindromic prime factors 26 x 32 x 112, it is also the largest ' smoothly undulating ' (of the form ababab...) square known to humanity. Visit Sloane's database to find out the other smaller undulating squares at A016073. I submitted a variant namely ' undulating primes ', watch out for entry A032758.
A less known fact (!?) is that 69696 is also the largest palindromic substring in 8117.
Thanks to G. L. Honaker, Jr. we know that 69696 is also the sum of a Twin Prime Pair.
Garland reports the following from “NUMBERS: Fun & Facts” by J. Newton Friend (1954) :
[ October 24, 2005 ]
Did you know that ( Bonus : 363 192 = 171 yet another palindrome popping up ! )
[ April 30, 2022 ]
69696 * 6996 = 487593216
69696 * 24242 = 1689570432
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A000026 Prime Curios! Prime Puzzle Richard Phillips Wikipedia 26 Le Nombre 26 Numberland 26 |
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