login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 19 18:13 EST 2020. Contains 331051 sequences. (Running on oeis4.)