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 A182644 #26 Feb 17 2023 22:25:32 %S A182644 1,2,6,14,34,82,198,470,1122,2662,6334,14970,35506,83734,198086, %T A182644 466314,1100818,2587634,6097830,14316402,33687146,79008870,185677006, %U A182644 435098774,1021404998,2391646494,5609151738,13125214770,30757286802,71928506630 %N A182644 Number of fixed snake polyominoes with n cells. %C A182644 This sequence counts snake polyominoes both with and without holes; for example, it counts all four of these 7-cell snakes: %C A182644 ### ## ## ### %C A182644 # # # # # # # # %C A182644 ## ### ### ## %H A182644 Alain Goupil, Marie-Eve Pellerin, and Jérôme de Wouters d'Oplinter, <a href="https://arxiv.org/abs/1307.8432">Partially Directed Snake Polyominoes</a>, arXiv:1307.8432 [math.CO], 2013-2014. %Y A182644 Snake polyominoes by group of symmetries relating shapes considered the same: A002013 (all symmetries), A182644 (translations only), A151514 (rotations and translations), A151527 (horizontal and vertical reflections, rotations of order 2 and translations), A151524 (reflections in either diagonal, rotations of order 2 and translations), A151523 (rotations of order 2 and translations), A151526 (reflections in a horizontal line and translations), A182646 (reflections in a NE-SW diagonal line and translations). %K A182644 nonn %O A182644 1,2 %A A182644 _Joseph Myers_, Nov 24 2010 %E A182644 More terms from _Alain Goupil_ and _Jérôme de Wouters_, Jun 21 2014