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 A205586 #7 Jul 22 2025 18:56:32 %S A205586 2268,32500,541966,8952876,147377704,2444556894,40477518336, %T A205586 670667507098,11114946907896,184190072876610,3052516512565604, %U A205586 50588130338625662,838377567411023378,13894165181215493800,230263463379558919982 %N A205586 Number of (n+1)X5 0..2 arrays with no 2X2 subblock having the same number of equal edges as its horizontal or vertical neighbors, and new values 0..2 introduced in row major order. %C A205586 Column 4 of A205590 %H A205586 R. H. Hardin, <a href="/A205586/b205586.txt">Table of n, a(n) for n = 1..210</a> %e A205586 Some solutions for n=4 %e A205586 ..0..0..0..1..2....0..0..1..0..2....0..1..0..0..1....0..0..1..1..0 %e A205586 ..1..2..2..2..1....2..2..0..0..1....2..1..0..0..0....1..1..2..1..2 %e A205586 ..0..1..0..2..0....1..0..0..0..1....0..2..2..0..0....0..2..2..0..1 %e A205586 ..2..1..1..2..2....1..0..0..2..1....0..1..1..2..1....1..0..1..2..1 %e A205586 ..1..1..1..1..0....0..1..0..1..1....1..1..1..0..2....2..2..0..0..2 %K A205586 nonn %O A205586 1,1 %A A205586 _R. H. Hardin_ Jan 29 2012