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 A121156 #6 May 24 2018 18:10:08 %S A121156 1,1,6,18,73,240,841,2714,8758,27259,83847,252929,754737,2225129, %T A121156 6505344,18867696,54384446,155892016,444839696,1264336132,3581584336, %U A121156 10116577962,28505061687,80146304124,224929999040,630259883854,1763574118096,4928881367449 %N A121156 Number of monocyclic skeletons with n carbon atoms and a ring size of 9. %D A121156 Camden A. Parks and James B. Hendrickson, Enumeration of monocyclic and bicyclic carbon skeletons, J. Chem. Inf. Comput. Sci., vol. 31, 334-339 (1991). %H A121156 Andrew Howroyd, <a href="/A121156/b121156.txt">Table of n, a(n) for n = 9..200</a> %Y A121156 Column k=9 of A305059. %K A121156 nonn %O A121156 9,3 %A A121156 _Parthasarathy Nambi_, Aug 13 2006 %E A121156 Terms a(26) and beyond from _Andrew Howroyd_, May 24 2018