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 A204974 #8 Jul 22 2025 18:28:55 %S A204974 11,726,16813,451468,11815256,311275169,8202482914,216132492162, %T A204974 5694910498914,150054777556991,3953775892498008,104177764014536592, %U A204974 2744972159153714019,72327078831355250520,1905740996306739704109 %N A204974 Number of nX4 0..2 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..2 introduced in row major order. %C A204974 Column 4 of A204978 %H A204974 R. H. Hardin, <a href="/A204974/b204974.txt">Table of n, a(n) for n = 1..210</a> %e A204974 Some solutions for n=5 %e A204974 ..0..1..0..1....0..0..1..1....0..0..1..1....0..1..1..0....0..1..2..0 %e A204974 ..2..0..1..1....1..0..1..1....2..0..0..2....1..2..2..1....1..2..2..0 %e A204974 ..2..0..2..2....1..2..2..0....0..1..2..2....2..2..1..0....0..1..1..2 %e A204974 ..0..1..2..2....2..2..1..0....2..1..1..0....0..0..1..2....0..1..2..1 %e A204974 ..2..1..0..0....0..0..1..1....2..2..0..2....2..2..0..2....2..0..2..2 %K A204974 nonn %O A204974 1,1 %A A204974 _R. H. Hardin_ Jan 21 2012