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 A231966 #7 Nov 19 2013 13:11:00 %S A231966 10,21,55,110,253,1081,1265,1711,2530,3403,5671,11891,13861,15931, %T A231966 25651,34453,59455,60031,64261,73153,108811,114481,118910,126253, %U A231966 158203,171991,258121,351541,371953,392941,482653,518671,568301,703891,822403,853471,869221,933661 %N A231966 Squarefree numbers (from A005117) with prime divisors in a 2p+1 progression. %C A231966 Squarefree numbers with k>=2 prime divisors of the form p_1 * p_2 * … * p_k, where p_1 < p_2 < … < p_k = primes with p_k = 2 * p_(k-1) + 1. %C A231966 Supersequence of A156592 (numbers of the form p*q, p and q prime with q=2*p+1; see A005384 and A005385). %e A231966 118910 = 2*5*11*23*47, where 5 = 2*2 + 1, 11 = 2*5 + 1, 23 = 2*11 + 1, 47 = 2*23 + 1. %Y A231966 Cf. A005117, A156592, A005384, A005385, A000040, A231967, A231968, A231969. %K A231966 nonn %O A231966 1,1 %A A231966 _Jaroslav Krizek_, Nov 16 2013