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 A197550 #12 Feb 03 2023 16:31:40 %S A197550 1,3,7,28,99,433,1852,8463,38798,181889,858570,4093739,19636172, %T A197550 94759074 %N A197550 Number of free poly-IH8-tiles (holes allowed) with n cells. %C A197550 Equivalently, one-sided polybricks, or polyhexes where two polyhexes are considered equivalent if and only if they are related by a translation or a rotation of order 2. %D A197550 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4. %H A197550 Tom McLean, <a href="https://www.jaapsch.net/tilings/mclean/html/ih8.html">IH8</a>. %Y A197550 Cf. A000228, A001207, A006535, A057973, A197549, A197551, A197552, A197553, A197554. %K A197550 hard,nonn,more %O A197550 1,2 %A A197550 _Joseph Myers_, Oct 16 2011