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 A121975 #4 Mar 30 2012 17:25:50 %S A121975 2,100,2276,38500,525764,6229444,66405417,652844870,6018548260 %N A121975 Number of isomeric aza-benzenoids with seven nitrogen atoms. %D A121975 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 A121975 If n=5 then the number of isomeric aza-benzenoids with seven nitrogen atoms is 38500. Here n is the number of hexagons. %K A121975 nonn %O A121975 2,1 %A A121975 _Parthasarathy Nambi_, Sep 05 2006