

A117773


Number of palindromic primes in base 2 with exactly n binary digits.


2



0, 1, 2, 0, 2, 0, 3, 0, 3, 0, 7, 0, 12, 0, 23, 0, 40, 0, 94, 0, 142, 0, 271, 0, 480, 0, 856, 0, 1721, 0, 3099, 0, 5572, 0, 10799, 0, 20782, 0, 39468, 0, 72672, 0, 139867, 0, 274480, 0, 520376, 0, 986318, 0, 1914097, 0, 3726617, 0, 7107443, 0, 13682325, 0, 26430797, 0, 51412565, 0, 99204128, 0, 190457946, 0
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,3


COMMENTS

Every palindrome with an even number of digits is divisible by 11 (in base 2), i.e. by 3 in base 10, and therefore is composite (not prime). Hence there is only one palindromic prime with an even number of digits, namely 11_2 = 3_{10}.


LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..76
Eric Weisstein's World of Mathematics, Palindromic Prime.


CROSSREFS

Cf. A016041, A117697, A095741.
Sequence in context: A242096 A284965 A274101 * A025805 A029192 A128619
Adjacent sequences: A117770 A117771 A117772 * A117774 A117775 A117776


KEYWORD

nonn,base


AUTHOR

Martin Renner, Apr 15 2006


EXTENSIONS

a(23)a(40) from Donovan Johnson, Dec 02 2009
a(41)a(66) from Martin Raab, Oct 20 2015


STATUS

approved



