This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A157356 #2 Mar 31 2012 12:38:20
%S A157356 253,517,1081,1837,3841,3949,7849,7909,8257,15829,16537,16873,22429,
%T A157356 31669,33097,33793,44869,45397,46897,54109,59953,62029,63877,65197,
%U A157356 66217,66517,67633,79717,83149,83677,84997,93817,94921,95833,108229
%N A157356 Products (semiprimes) of two distinct double-safe primes.
%C A157356 253=11*23; 11 and 23 are double safe prime numbers; (11-1)/2=5; (5-1)/2=2(prime); (23-1)/2=11; (11-1)/2=5(prime), ...
%t A157356 lst={};Do[If[Plus@@Last/@FactorInteger[n]==2,a=Length[First/@FactorInteger[n]];If[a==2,b=First/@FactorInteger[n];c=b[[1]];d=b[[2]];If[PrimeQ[cx=(c-1)/2]&&PrimeQ[(cx-1)/2]&&PrimeQ[dx=(d-1)/2]&&PrimeQ[(dx-1)/2],AppendTo[lst,n]]]],{n,9!}];lst
%Y A157356 Cf. A001358, A005384, A005385, A006881, A007304, A066179, A111206, A157342, A157344, A157345, A157346, A157347, A157352, A157353, A157354, A157355
%K A157356 nonn
%O A157356 1,1
%A A157356 _Vladimir Joseph Stephan Orlovsky_, Feb 27 2009