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 A240628 #9 Feb 01 2025 23:19:28 %S A240628 40,16624,7462748,3367163455,1519699081714,685854075788477, %T A240628 309535605539765299,139697630796640339536,63047448929964784303613, %U A240628 28454174772679454861874697,12841757682871155282688313826,5795660627332850278874835069098,2615660794724892372200960575345057 %N A240628 Number of n X 5 0..3 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..3 introduced in row major order. %H A240628 R. H. Hardin, <a href="/A240628/b240628.txt">Table of n, a(n) for n = 1..25</a> %e A240628 Some solutions for n=2: %e A240628 ..0..1..2..1..1....0..1..2..1..2....0..1..0..2..0....0..0..1..0..2 %e A240628 ..0..1..2..0..3....3..1..0..2..1....2..2..0..1..3....3..2..3..3..2 %Y A240628 Column 5 of A240629. %K A240628 nonn %O A240628 1,1 %A A240628 _R. H. Hardin_, Apr 09 2014