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 A089538 #6 Mar 30 2012 17:29:13 %S A089538 2,1,2,0,0,0,0,0,3,0,2,7,0,0,4,1,2,9,0,0,5,10,2,0,0,0,12,0,13,1,8,5,5, %T A089538 0,4,2,13,0,6,31,15,17,1,12,3,12,17,0,1,21,17,22,21,0,0,18,0,12,0,18, %U A089538 11,12,14,4,23,20,8,4,27,8,0,28,12,39,0,27,2,21,29,25 %N A089538 A085747 indexed by A000040. %F A089538 a(n)=k such that A085747(n)=A000040(k) if A085747(n) is prime, otherwise 0. %Y A089538 Cf. A085747, A089539, A089540, A089541. %K A089538 nonn %O A089538 1,1 %A A089538 _Ray Chandler_, Nov 09 2003 %E A089538 More terms from _Max Alekseyev_, Jun 17 2011