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 A098668 #3 Mar 30 2012 18:50:47 %S A098668 1,2,3,2,5,1,7,8,9,1,11,1,13,2,5,8,17,9,19,1,7,2,23,4,25,1,27,2,29,1, %T A098668 31,32,11,1,7,3,37,1,13,20,41,3,43,2,3,1,47,16,49,25,51,1,53,9,11,8, %U A098668 19,1,59,1,61,2,9,32,65,1,67,1,23,7,71,36,73,1,25,2,11,1,79,16,81,1,83,7,17 %N A098668 Right edge of triangle A098666. %C A098668 a(n) = A098666(n,n); %C A098668 a(n) = n iff n=1 or n is prime. %K A098668 nonn %O A098668 1,2 %A A098668 _Reinhard Zumkeller_, Sep 20 2004