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 A112232 #4 Mar 30 2012 18:50:53 %S A112232 1,2,3,4,4,5,6,6,7,8,8,9,9,10,10,11,12,12,13,14,14,15,15,16,16,17,18, %T A112232 18,19,20,20,21,21,22,22,23,24,24,25,25,26,26,27,27,28,28,29,30,30,31, %U A112232 32,32,33,33,34,34,35,35,36,36,37,38,38,39,39,40,40,41,42,42,43,44,44,45 %N A112232 Repeat each composite number in the sequence of natural numbers. %C A112232 a(n) = A112233(n) - A112231(n); %C A112232 a(n + A002808(n) - 1) = A002808(n), %C A112232 a(n + A002808(n)) = A002808(n), %C A112232 a(n + A002808(n) + 1) = A002808(n) + 1. %K A112232 nonn %O A112232 1,2 %A A112232 _Reinhard Zumkeller_, Aug 29 2005