%I A002504 M0522 N0188
%S A002504 2,3,4,5,7,10,11,12,14,15,18,24,25,26,28,29,31,33,35,38,39,42,43,46,49,
%T A002504 50,53,56,59,63,64,67,68,75,81,82,87,89,91,92,94,96,106,109,120,124,126,
%U A002504 129,130,137,141,143,148,154,157,158,159,165,166,171,172,173,176,180
%N A002504 Values of x in A002407, i.e. numbers such that 1+3x(x-1) is (a "cuban") 
               prime.
%D A002504 A. J. C. Cunningham, On quasi-Mersennian numbers, Mess. Math., 41 (1912), 
               119-146.
%D A002504 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002504 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%e A002504 a(1) = 2 since A002407(1)=7=1+3k(k-1) with k=2 is the smallest prime 
               of that form.
%o A002504 (PARI) for(k=1,999,isprime(3*k*(k-1)+1)&print1(k",")) \\ - M. F. Hasler, 
               Nov 28 2007
%Y A002504 Cf. A133431.
%Y A002504 Sequence in context: A094617 A047502 A117092 this_sequence A133431 A123091 
               A160512
%Y A002504 Adjacent sequences: A002501 A002502 A002503 this_sequence A002505 A002506 
               A002507
%K A002504 nonn
%O A002504 1,1
%A A002504 N. J. A. Sloane (njas(AT)research.att.com).
%E A002504 Edited, updated (1 is no longer regarded as a prime) and extended by 
               M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 28 2007