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 A121949 #4 Mar 30 2012 17:25:49 %S A121949 1,2,10,43,210,1026,5130,25770,130350,661458 %N A121949 Number of isomeric aza-benzenoids with one nitrogen atom and n hexagons. %D A121949 N. Trinajstich, Z. Jericevic, J. V. Knop, W. R. Muller and K. Szymanski, "Computer generation of isomeric structures", Pure and Appl. Chem., vol. 55 (1983) pp. 379-390. %e A121949 If n=5 then the number of isomeric aza-benzenoids with one nitrogen atom is 210. Here n is the number of hexagons. %K A121949 nonn %O A121949 1,2 %A A121949 _Parthasarathy Nambi_, Sep 04 2006