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 A205158 #10 Feb 01 2025 19:56:22 %S A205158 40,31168,15821727,8797534495,4826926610498,2654271236904226, %T A205158 1458877292453477918,801931987315155805350,440804977416966931974046, %U A205158 242302335602851559365684237,133188963363707384391102837136,73211445306645369967259855981514,40242939870572168051645146035499410 %N A205158 Number of n X 5 0..3 arrays with no occurrence of three equal elements in a row horizontally, vertically or nw-to-se diagonally, and new values 0..3 introduced in row major order. %H A205158 R. H. Hardin, <a href="/A205158/b205158.txt">Table of n, a(n) for n = 1..33</a> %e A205158 Some solutions for n=5: %e A205158 ..0..0..1..0..0....0..0..1..0..1....0..1..1..0..0....0..0..1..0..0 %e A205158 ..2..1..3..2..2....0..2..2..1..0....0..0..1..0..0....2..0..3..0..2 %e A205158 ..2..2..3..2..2....3..1..0..1..0....1..2..3..2..1....0..3..1..1..2 %e A205158 ..3..1..1..3..1....0..0..1..2..1....2..0..1..0..0....0..2..0..1..0 %e A205158 ..1..2..1..3..2....3..3..0..2..0....0..0..3..0..1....3..2..2..3..2 %Y A205158 Column 5 of A205161. %K A205158 nonn %O A205158 1,1 %A A205158 _R. H. Hardin_, Jan 22 2012