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 A221332 #6 Jun 02 2025 08:16:47 %S A221332 1,3363,571358,131347807,26135748494,5264460642473,1043094530574190, %T A221332 206296461646686083,40696390245562531399,8021014977002231894704, %U A221332 1580039716596918034100062,311140535645141827979564485 %N A221332 Number of 5Xn arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2. %C A221332 Row 5 of A221328 %H A221332 R. H. Hardin, <a href="/A221332/b221332.txt">Table of n, a(n) for n = 1..13</a> %e A221332 Some solutions for n=3 %e A221332 ..0..1..2....0..1..1....0..1..2....0..1..2....0..2..0....0..2..0....0..1..2 %e A221332 ..2..2..0....1..2..0....0..1..1....2..0..1....1..2..2....1..2..0....2..1..0 %e A221332 ..0..0..1....1..1..1....1..2..1....1..0..2....0..1..1....2..1..1....2..0..0 %e A221332 ..1..1..2....1..2..2....2..1..1....1..0..1....0..1..0....1..0..2....0..2..1 %e A221332 ..2..0..1....0..0..2....0..1..1....2..2..0....1..2..2....2..1..0....2..1..1 %K A221332 nonn %O A221332 1,2 %A A221332 _R. H. Hardin_ Jan 11 2013