A118573 Sophie Germain primes for which the reversal is also a Sophie Germain prime.

2, 3, 5, 11, 131, 191, 359, 953, 1229, 1583, 3851, 9221, 10061, 11579, 11939, 12119, 12821, 13619, 14081, 14741, 14939, 15791, 15803, 16001, 16883, 18041, 19163, 19391, 19751, 19991, 30851, 31859, 32633, 33623, 33809, 35993, 36191, 36563

Offset

1,1

Comments

{k such that k is in A005384 and A004086(k) is in A005384}. - Jonathan Vos Post, Apr 18 2008

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

359 is in the sequence because it is a Sophie Germain prime and its reversal 953 is also a Sophie Germain prime.

Mathematica

Select[Prime[Range[10000]], PrimeQ[2*# + 1] && PrimeQ[FromDigits[Reverse[ IntegerDigits[ # ]]]] && PrimeQ[2*FromDigits[Reverse[IntegerDigits[ # ]]] + 1] &] (* Stefan Steinerberger, May 18 2008 *)
fQ[n_] := (rp = FromDigits@ Reverse@ IntegerDigits@n; PrimeQ[2n + 1] && PrimeQ[rp] && PrimeQ[2rp + 1]); Select[Prime@ Range@4093, fQ@# &] (* Robert G. Wilson v, May 09 2006 *)

Crossrefs

Cf. A004086, A005384.

A051835 is a subsequence.

Sequence in context: A050444 A117701 A056163 * A051835 A075883 A195815

Adjacent sequences: A118570 A118571 A118572 * A118574 A118575 A118576

Keyword

base,nonn

Author

Luc Stevens (lms022(AT)yahoo.com), May 07 2006

Extensions

More terms from Robert G. Wilson v and Adam Panagos (adam.panagos(AT)gmail.com), May 09 2006

Edited by N. J. A. Sloane, Mar 02 2009 at the suggestion of R. J. Mathar

Status

approved