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 A156228 #20 May 06 2025 09:37:04 %S A156228 1,0,1,1,4,7,31,98,446,1894,9049,43151 %N A156228 Number of lakes in Conway's Game of Life with 8*n cells. %C A156228 a(n) is also the number of walks of length 4*n on a 2D lattice with the properties that: it turns 90 degrees after every step of length 1, it is a closed loop (i.e., it ends where it started) and it never crosses itself. %C A156228 In A266549, the walks are allowed to continue straight ahead. - _Pontus von Brömssen_, May 06 2025 %H A156228 Nathaniel Johnston, <a href="http://www.nathanieljohnston.com/2009/02/counting-lakes/">Counting Lakes</a> %H A156228 LifeWiki, <a href="http://www.conwaylife.com/wiki/Lake">Lakes</a> %e A156228 a(2) = 0 because there are no lakes with 16 cells. %Y A156228 Cf. A019473, A266549, A337550. %K A156228 nonn,hard,more %O A156228 1,5 %A A156228 _Nathaniel Johnston_, Feb 06 2009 %E A156228 a(11) and a(12) added by _Nathaniel Johnston_, Mar 09 2009