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 A365655 #13 Dec 04 2023 16:44:24
%S A365655 3,12,68,438,3054,22417,170610,1334316
%N A365655 Number of fixed n-polyominoids, allowing right-angled connections only ("hard" polyominoids).
%C A365655 Apparently, the definition of "hard" polyominoid in the Wikipedia article differs from the definition used here. Here, two squares are allowed to meet in a straight 180-degree connection provided that the structure be connected through right-angled ("hard") connections only; see A365654 for further details.
%H A365655 Wikipedia, <a href="https://en.wikipedia.org/wiki/Polyominoid">Polyominoid</a>.
%H A365655 <a href="/index/Pol#polyominoes">Index entries for sequences related to polyominoes</a>.
%Y A365655 Cf. A075678 (polyominoids), A365654 (free).
%Y A365655 13th and 17th row of A366767.
%K A365655 nonn,hard,more
%O A365655 1,1
%A A365655 _Pontus von Brömssen_, Sep 17 2023