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 A309159 #19 Jul 31 2019 07:18:35 %S A309159 1,2,2,4,10,28,79,235,720,2254,7146,22927,74137,241461,790838,2603210, %T A309159 8604861,28549166,95027832,317229779,1061764660,3562113987,11976146355 %N A309159 Number of generalized polyforms on the snub square tiling with n cells. %C A309159 The generalized polyforms counted by this sequence are "free", which means that they are counted up to rotation and reflection. %H A309159 Peter Kagey, <a href="https://codegolf.stackexchange.com/q/187763/53884">Counting generalized polyominoes</a> %H A309159 Wikipedia, <a href="https://en.wikipedia.org/wiki/Snub_square_tiling">Snub square tiling</a> %Y A309159 Cf. A000105, A000228, A000577. %K A309159 nonn %O A309159 0,2 %A A309159 _Peter Kagey_ and Peter Taylor, Jul 15 2019 %E A309159 a(19)-a(22) from _Christian Sievers_