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 A091013 #3 Mar 30 2012 18:50:43 %S A091013 12,18,24,30,36,42,45,48,54,56,60,66,72,75,78,80,84,90,96,102,105,108, %T A091013 112,114,120,126,132,135,138,140,144,150,156,160,162,165,168,174,180, %U A091013 182,186,192,195,196,198,200,204,210,216,222,224,225,228,231,234,240 %N A091013 Numbers having more than one divisor d such that for some x also d-x and d+x are divisors. %C A091013 A091009(a(n)) > 1. %Y A091013 Cf. A091012, A091011, A091010. %K A091013 nonn %O A091013 1,1 %A A091013 _Reinhard Zumkeller_, Dec 13 2003