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 A038144 #21 May 15 2023 11:34:27 %S A038144 0,0,0,0,0,1,2,13,67,404,2323,13517,76570,429320,2373965,13004323, %T A038144 70641985,381260615,2046521491,10936624026,58228136539 %N A038144 Number of planar n-hexes, or polyhexes (in the sense of A000228, so rotations and reflections count as the same shape) with at least one hole. %C A038144 Apparently the same as the number of hexagonal planar circulenes (planar rings of hexagons) with n cells, although the two sequences may in fact differ for large n. %D A038144 J. V. Knop et al., On the total number of polyhexes, Match, No. 16 (1984), 119-134. %H A038144 Craig Knecht, <a href="/A038144/a038144.png">Tiling of a fixed pattern of holes in a frame.</a> %H A038144 J. V. Knop, K. Szymanski, Ž. Jeričević, and N. Trinajstić, <a href="http://match.pmf.kg.ac.rs/electronic_versions/Match16/match16_119-134.pdf">On the total number of polyhexes</a>, Match, No. 16 (1984), 119-134. %H A038144 Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyomino, polyhex and polyiamond tiling</a> %Y A038144 Cf. A018190, A038143, A038147, A000228, A018190. %K A038144 nonn %O A038144 1,7 %A A038144 _N. J. A. Sloane_ %E A038144 More terms from _Joseph Myers_, May 05 2002 %E A038144 Further terms from _Joseph Myers_, Nov 06 2003 %E A038144 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007 %E A038144 Link edited by _Joseph Myers_, Nov 17 2010