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 A066331 #8 Oct 08 2023 21:17:22 %S A066331 1,3,9,29,99,348,1260,4644,17382,65822,251655,969819,3762517,14680890, %T A066331 57567228,226712655,896252850,3555116583,14144563158 %N A066331 Number of fixed hexagonal polyominoes with n cells and tree-like structure. %H A066331 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a066/A066331.java">Java program</a> (github) %Y A066331 Cf. A001207 (all polyhexes), A038142 (free tree-like). %K A066331 nonn,more %O A066331 1,2 %A A066331 _Jan Kristian Haugland_, Jan 01 2002 %E A066331 a(16)-a(19) from _Sean A. Irvine_, Oct 08 2023