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 A026252 #4 Mar 30 2012 18:56:05 %S A026252 2,1,7,9,12,14,3,19,4,24,26,5,31,6,36,38,41,43,8,48,50,53,55,10,60,11, %T A026252 65,67,70,72,13,77,79,82,84,15,89,16,94,96,17,101,18,106,108,111,113, %U A026252 20,118,21,123,125,22,130,23,135,137,140,142 %N A026252 a(n) = (1/2)*(s(n) + 1), where s(n) is the n-th odd number in A026250. Also a(n) = position of n in A026252. %K A026252 nonn %O A026252 1,1 %A A026252 _Clark Kimberling_