%I A156658
%S A156658 2,3,5,7,11,23,29,41,47,53,59,83,89,107,113,131,167,173,179,191,227,233,
%T A156658 239,251,263,281,293,347,359,383,419,431,443,467,479,491,503,509,563,
%U A156658 587,593,641,653,659,683,719,743,761,809,839,863,887,911,953,983,1013
%N A156658 Primes p such that also 2*p+1 or (p-1)/2 is prime.
%C A156658 Union of A005384 and A005385;
%C A156658 A156660(a(n)) + A156659(a(n)) > 0;
%C A156658 primes occuring in Cunningham chains of the first kind.
%C A156658 A156876 gives the number of these numbers <= n. [From Reinhard Zumkeller 
               (reinhard.zumkeller(AT)gmail.com), Feb 18 2009]
%H A156658 Wikipedia, <a href="http://en.wikipedia.org/wiki/Sophie_Germain_prime">
               Sophie Germain prime</a>
%H A156658 Wikipedia, <a href="http://en.wikipedia.org/wiki/Safe_prime">Safe prime</
               a>
%H A156658 Wikipedia, <a href="http://en.wikipedia.org/wiki/Cunningham_chain">Cunningham 
               chain</a>
%Y A156658 A059500.
%Y A156658 Sequence in context: A089392 A089695 A070027 this_sequence A118723 A118721 
               A094318
%Y A156658 Adjacent sequences: A156655 A156656 A156657 this_sequence A156659 A156660 
               A156661
%K A156658 nonn
%O A156658 1,1
%A A156658 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 13 2009