[ March 1999 ]
An original puzzle involving primes
Enoch Haga

Enoch Haga himself discovered two nice solutions for this hard problem.

At 73, the 21^st prime, the sum of the primes ⩽ 73 is 712
from which the palindrome 21712 is formed.
At 4177, the 574^th prime, the sum of the primes ⩽ 4177 is 1111475
from which the palindrome 5741111475 is formed.

Apparently not easy to find, Enoch dares to challenge you to find more solutions !
"I have now checked to 199909, the 17978 ^th prime, and found nothing else to con-cat-enate!
Perhaps there are no more, but then I shall offer a prize of $5.95
(the sum of 21 and 574 divided by 100 -- just because it forms a palindrome)
to anyone discovering the next one in sequence (or who proves that it is impossible)."

[ August 15, 2002 ]
Jean Claude Rosa distinguished more cases that could be examined.

Let P be the prime number, N its rank number,
S the sum of the prime numbers ⩽ P,
& the concatenation operation and
PP the result that must be palindromic.

JCR proposes the following six 'equations' to solve !

By varying P from 2 up to 1175497783 JCR obtained the following results :