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 A204701 #8 Jul 22 2025 18:14:35 %S A204701 11,726,22869,835135,29846373,1074195735,38585324821,1386815731346, %T A204701 49835668719324,1790952554181415,64360800888516224, %U A204701 2312920275315600518,83118816237627091277,2987020411865810161864,107343805323748931471929 %N A204701 Number of nX4 0..2 arrays with no occurrence of three equal elements in a row horizontally, vertically or nw-to-se diagonally, and new values 0..2 introduced in row major order. %C A204701 Column 4 of A204705 %H A204701 R. H. Hardin, <a href="/A204701/b204701.txt">Table of n, a(n) for n = 1..210</a> %e A204701 Some solutions for n=5 %e A204701 ..0..1..0..2....0..1..2..0....0..1..0..2....0..1..0..1....0..1..2..2 %e A204701 ..2..2..0..1....1..2..2..0....1..2..2..1....2..2..1..0....0..0..1..2 %e A204701 ..2..0..1..1....0..1..1..2....1..0..1..1....1..1..0..0....1..2..2..0 %e A204701 ..0..1..0..2....0..1..2..1....0..0..2..0....2..0..0..1....1..0..0..1 %e A204701 ..1..2..2..1....2..2..0..0....0..2..0..0....0..1..1..0....2..2..1..2 %K A204701 nonn %O A204701 1,1 %A A204701 _R. H. Hardin_ Jan 18 2012