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 A151514 #25 Feb 16 2025 08:33:09 %S A151514 1,1,2,5,10,24,53,126,289,686,1604,3792,8925,21051,49638,116858, %T A151514 275480,647573,1525113,3580673,8423334,19755938,46422915,108783480, %U A151514 255359883,597932342,1402308318,3281352516,7689369625,17982241557,42108302007,98422076879,230322745835 %N A151514 Number of 1-sided snake polyominoes with n cells. %C A151514 A snake polyomino has 2 cells with 1 neighbor each, and (n-2) cells with 2 neighbors each. - _Arthur O'Dwyer_, Dec 12 2022 %H A151514 Arthur O'Dwyer, <a href="https://quuxplusone.github.io/blog/2022/12/08/polyomino-snakes/">Polyomino strips, snakes, and ouroboroi</a>, Dec 10 2022. %H A151514 Ed Pegg, Jr., <a href="http://demonstrations.wolfram.com/PolyformExplorer/">Illustrations of polyforms</a> %H A151514 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polyomino.html">Polyomino</a> %Y A151514 A002013 counts 2-sided (free) snake polyominoes. %Y A151514 A359068 gives the number of 1-sided strip polyominoes (that is, snakes without holes) with n cells; A359068(n) < A151514(n) for n >= 7. %K A151514 nonn,hard,more %O A151514 1,3 %A A151514 _Ed Pegg Jr_, May 13 2009 %E A151514 a(15)-a(23) from _Joseph Myers_, Nov 22 2010 %E A151514 a(24)-a(29) from _Arthur O'Dwyer_, Dec 10 2022 %E A151514 a(30)-a(33) from _Arthur O'Dwyer_, Jan 19 2023