A117777 Total number of palindromic primes in base 4 below 4^n.

2, 3, 6, 6, 16, 16, 45, 45, 142, 142, 435, 435, 1417, 1417, 4802, 4802, 16433, 16433, 57808, 57808, 210708, 210708, 752233, 752233, 2748264, 2748264, 10211513, 10211513, 38013234, 38013234, 140417288, 140417288

Offset

1,1

Comments

Every palindrome with an even number of digits is divisible by 11 (in base 4) and therefore is composite (not prime). Hence there is only one palindromic prime with an even number of digits.

Links

Table of n, a(n) for n=1..32.

Eric Weisstein's World of Mathematics, Palindromic Prime.

Crossrefs

Partial sums of A117778.

Cf. A029972, A117699.

Cf. A117772, A117775, A117779, A117781, A117783, A117785, A117787.

Sequence in context: A339546 A007894 A102625 * A371991 A223547 A049297

Adjacent sequences: A117774 A117775 A117776 * A117778 A117779 A117780

Keyword

nonn,base,more

Author

Martin Renner, Apr 15 2006

Extensions

a(13)-a(32) from the data at A117778 added by Amiram Eldar, Mar 21 2021

Status

approved