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 A186164 #7 Jul 22 2025 10:17:11 %S A186164 7,2175,253341,37402872,5033988714,704281652979,96951738076992, %T A186164 13435825601048421,1856827788245959473,256908205340960558187, %U A186164 35528479510856892673200,4914300705034627821533085 %N A186164 1/4 the number of nX5 0..3 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors. %C A186164 Column 5 of A186168 %H A186164 R. H. Hardin, <a href="/A186164/b186164.txt">Table of n, a(n) for n = 1..21</a> %e A186164 Some solutions for 4X5 with a(1,1)=0 %e A186164 ..0..0..0..1..1....0..0..0..0..0....0..0..0..3..3....0..0..0..2..2 %e A186164 ..0..2..0..1..2....0..2..1..1..1....0..2..0..1..3....0..2..0..2..1 %e A186164 ..1..2..2..1..2....0..2..2..3..3....0..2..2..1..1....0..2..0..3..1 %e A186164 ..1..1..0..0..2....3..3..3..0..0....0..3..3..0..0....0..2..0..3..3 %K A186164 nonn %O A186164 1,1 %A A186164 _R. H. Hardin_ Feb 13 2011