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 A121972 #4 Mar 30 2012 17:25:49 %S A121972 1,14,216,2442,24611,223717,1894520,15169211,116213717,8588186640 %N A121972 Number of isomeric aza-benzenoids with five nitrogen atoms. %D A121972 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 A121972 If n=5 then the number of isomeric aza-benzenoids with five nitrogen atoms is 24611. Here n is the number of hexagons. %K A121972 nonn %O A121972 1,2 %A A121972 _Parthasarathy Nambi_, Sep 05 2006