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 A205307 #11 Feb 01 2025 23:19:06 %S A205307 40,31168,19490790,13049279920,8615950028840,5705396521337690, %T A205307 3775750320744043966,2499057571450100571862,1654008038632602002195374, %U A205307 1094715856585124185784208270,724543877252168299768908602288,479543578578238224536612339956838,317388689777679827724542588307647638 %N A205307 Number of n X 5 0..3 arrays with no occurrence of three equal elements in a row horizontally or vertically, and new values 0..3 introduced in row major order. %H A205307 R. H. Hardin, <a href="/A205307/b205307.txt">Table of n, a(n) for n = 1..96</a> %e A205307 Some solutions for n=5: %e A205307 ..0..0..1..1..2....0..1..0..1..0....0..1..1..0..0....0..1..0..2..0 %e A205307 ..0..2..2..1..2....0..0..1..1..2....0..0..1..0..0....3..3..0..1..3 %e A205307 ..1..0..1..0..3....3..2..3..0..1....1..2..3..1..1....2..1..1..2..1 %e A205307 ..2..0..1..3..2....1..1..2..2..1....2..0..1..0..0....1..0..2..0..3 %e A205307 ..0..1..0..0..1....2..3..0..1..2....0..0..3..0..1....0..0..2..1..1 %Y A205307 Column 5 of A205310. %K A205307 nonn %O A205307 1,1 %A A205307 _R. H. Hardin_, Jan 25 2012