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 A205157 #8 Jul 22 2025 18:35:26 %S A205157 12,2191,332285,54314298,8797534495,1427843505563,231638725420288, %T A205157 37582214286016391,6097402008530516671,989257097238735049744, %U A205157 160499289951117243179507,26039769955147853451399045 %N A205157 Number of nX4 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. %C A205157 Column 4 of A205161 %H A205157 R. H. Hardin, <a href="/A205157/b205157.txt">Table of n, a(n) for n = 1..210</a> %e A205157 Some solutions for n=5 %e A205157 ..0..1..1..0....0..0..1..0....0..0..1..0....0..1..0..0....0..1..0..2 %e A205157 ..0..0..2..0....2..1..0..1....2..0..3..1....0..1..0..0....0..3..3..0 %e A205157 ..1..2..1..1....0..1..1..2....1..2..1..2....1..0..1..1....1..3..2..1 %e A205157 ..3..1..0..0....3..2..1..2....0..1..0..3....2..3..1..3....1..2..1..1 %e A205157 ..1..0..2..3....3..3..0..3....2..2..3..2....2..2..3..1....0..2..0..3 %K A205157 nonn %O A205157 1,1 %A A205157 _R. H. Hardin_ Jan 22 2012