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 A057779 #22 Jun 17 2022 03:18:14 %S A057779 0,0,1,0,1,1,3,2,12,14,50,98,313,750,2308,6270 %N A057779 Number of hexagonal polyominoes (or polyhexes, A000228) with perimeter 2n. %H A057779 Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/IsopolyH.htm">Isoperimetrical Polyhexes</a> %H A057779 <a href="/A057779/a057779.gif">Picture from Andrew Clarke's page showing the polyhexes of perimeters 6, 8, ... 16.</a> %Y A057779 Cf. A000228, A000105, A057730, A258206 (counts only polyhexes without holes). %K A057779 nonn,nice,more %O A057779 1,7 %A A057779 _N. J. A. Sloane_, Oct 29 2000 %E A057779 Link updated by _William Rex Marshall_, Dec 16 2009 %E A057779 a(13)-a(16) from _John Mason_, Jul 26 2021