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 A186557 #7 Jul 22 2025 10:25:01 %S A186557 927477,783375343,663296784123,561714653720250,475681559860717916, %T A186557 402827283017904807331,341131017852900112413067, %U A186557 288884064380556803805427879,244639147969972250796140260427 %N A186557 Number of (n+1)X5 0..3 arrays with no 2X2 subblock commuting with any of its horizontal and vertical 2X2 subblock neighbors. %C A186557 Column 4 of A186558 %H A186557 R. H. Hardin, <a href="/A186557/b186557.txt">Table of n, a(n) for n = 1..13</a> %e A186557 Some solutions for 3X5 %e A186557 ..0..0..0..0..1....0..0..0..2..3....2..0..3..2..3....2..0..3..2..1 %e A186557 ..2..0..2..0..0....2..0..2..0..3....2..0..2..0..3....2..0..2..3..2 %e A186557 ..0..0..2..1..2....0..0..1..0..3....0..0..2..2..1....0..0..1..3..3 %K A186557 nonn %O A186557 1,1 %A A186557 _R. H. Hardin_ Feb 23 2011