A117783 Total number of palindromic primes in base 7 below 7^n.

3, 3, 9, 9, 50, 50, 204, 204, 1135, 1135, 6086, 6086, 36018, 36018, 216932, 216932, 1306070, 1306070, 8129138, 8129138, 51773946, 51773946, 326701423, 326701423

Offset

1,1

Comments

Every palindrome with an even number of digits is divisible by 11 (in base 7) 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..24.

Eric Weisstein's World of Mathematics, Palindromic Prime.

Crossrefs

Partial sums of A117784.

Cf. A029975, A117702.

Cf. A117772, A117775, A117777, A117779, A117781, A117785, A117787.

Sequence in context: A170832 A232281 A223743 * A121445 A327798 A121074

Adjacent sequences: A117780 A117781 A117782 * A117784 A117785 A117786

Keyword

nonn,base,more

Author

Martin Renner, Apr 15 2006

Extensions

a(9)-a(24) from the data at A117784 added by Amiram Eldar, Mar 21 2021

Status

approved