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 A156541 #10 Aug 30 2015 10:11:12 %S A156541 1,2,3,4,5,6,8,9,10,11,12,15,16,18,20,22,23,24,25,27,29,30,32,33,36, %T A156541 40,41,44,45,46,48,50,53,54,55,58,60,64,66,69,72,75,80,81,82,83,87,88, %U A156541 89,90,92,96,99,100,106,108,110,113,115,116,120,121,123,125,128,131,132 %N A156541 Multiplicative closure of Sophie Germain primes (A005384). %C A156541 A156542(a(n)) = A001221(a(n)); %C A156541 Subsequence of A130176. %H A156541 R. Zumkeller, <a href="/A156541/b156541.txt">Table of n, a(n) for n = 1..1000</a> %t A156541 Select[Range@132, And @@ PrimeQ[FactorInteger[#][[All, 1]]*2 + 1] &] (* _Ivan Neretin_, Aug 30 2015 *) %Y A156541 Cf. A156541, A156543. %K A156541 nonn %O A156541 1,2 %A A156541 _Reinhard Zumkeller_, Feb 10 2009