A117779 Total number of palindromic primes in base 5 below 5^n.

2, 2, 7, 7, 25, 25, 83, 83, 243, 243, 1038, 1038, 4205, 4205, 17724, 17724, 78553, 78553, 349246, 349246, 1526658, 1526658, 7028772, 7028772, 32055014, 32055014, 146939924, 146939924

Offset

1,1

Comments

Every palindrome with an even number of digits is divisible by 11 (in base 5) and therefore is composite (not prime). Hence there is no palindromic prime with an even number of digits.

Links

Table of n, a(n) for n=1..28.

Eric Weisstein's World of Mathematics, Palindromic Prime.

Crossrefs

Partial sums of A117780.

Cf. A029973, A117700.

Cf. A117772, A117775, A117777, A117781, A117783, A117785, A117787.

Sequence in context: A244049 A271229 A199886 * A300952 A195326 A263868

Adjacent sequences: A117776 A117777 A117778 * A117780 A117781 A117782

Keyword

nonn,base,more

Author

Martin Renner, Apr 15 2006

Extensions

a(11)-a(28) from the data at A117780 added by Amiram Eldar, Mar 21 2021

Status

approved