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 A209742 #7 Jul 22 2025 21:56:47 %S A209742 203,183240,404495219,991613495404,2462887498725440, %T A209742 6126537051572916244,15242797658314710633378, %U A209742 37924827001459049241306782,94359067187520965488130465180,234770648430435211602772504683016 %N A209742 Number of nX6 0..5 arrays with every 2X2 subblock containing exactly one value repeat, and new values 0..5 introduced in row major order. %C A209742 Column 6 of A209744 %H A209742 R. H. Hardin, <a href="/A209742/b209742.txt">Table of n, a(n) for n = 1..210</a> %e A209742 Some solutions for n=5 %e A209742 ..0..0..0..0..0..0....0..0..0..0..0..0....0..1..0..0..1..0....0..0..1..2..1..0 %e A209742 ..1..2..1..3..2..1....1..2..1..2..1..3....2..0..2..1..2..0....1..3..0..0..0..2 %e A209742 ..3..1..0..0..0..1....3..1..3..3..1..0....2..1..0..0..2..1....0..0..4..1..4..2 %e A209742 ..2..3..1..2..3..0....3..0..0..1..0..4....0..1..2..3..0..0....5..2..4..2..1..2 %e A209742 ..0..2..2..0..2..2....5..5..3..3..0..1....2..1..0..0..1..2....1..5..4..5..1..5 %K A209742 nonn %O A209742 1,1 %A A209742 _R. H. Hardin_ Mar 12 2012