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 A133016 #2 Mar 30 2012 17:33:49 %S A133016 1,2,4,5,6,7,8,9,10,11,12,13,15,16,17,18,19,20,21,22,23,24,25,26,27, %T A133016 28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50, %U A133016 51,52,53,54,55,56,57,58,59,60,61,62,63,64 %N A133016 Even imperfect numbers, divided by 2. %Y A133016 Cf. A005843, A014335, A014445, A014494, A026503, A028334. Imperfect numbers: A132999. %K A133016 easy,nonn %O A133016 1,2 %A A133016 _Omar E. Pol_, Oct 20 2007