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 A123355 #8 Jul 26 2019 04:24:54 %S A123355 1,3,20,155,1315,11957,114972,1157650,12115220,131015260 %N A123355 Kekulé numbers for certain benzenoids (see the Cyvin-Gutman book for details). %H A123355 Cyvin S.J., Gutman I. (1988) <a href="https://doi.org/10.1007/978-3-662-00892-8_11">Classes of Basic Benzenoids (III)</a>. In: Kekulé Structures in Benzenoid Hydrocarbons. Lecture Notes in Chemistry, vol 46. Springer, Berlin, Heidelberg (see p. 188) %K A123355 nonn %O A123355 0,2 %A A123355 _N. J. A. Sloane_, Oct 10 2006