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 A204225 #7 Jul 22 2025 17:48:29 %S A204225 2500,44641,752562,8183170,87487117,694547816,5466340007,34834605810, %T A204225 220710753856,1196535903414,6459574647599,30967790434185, %U A204225 148001428352179,644776741493252,2802681689033511,11319015179680230,45642521943090129 %N A204225 Number of (n+1)X4 0..2 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards. %C A204225 Column 3 of A204230 %H A204225 R. H. Hardin, <a href="/A204225/b204225.txt">Table of n, a(n) for n = 1..210</a> %e A204225 Some solutions for n=4 %e A204225 ..0..0..2..0....2..1..0..0....0..0..2..0....1..1..2..0....2..1..0..2 %e A204225 ..0..0..2..0....0..0..2..1....0..0..0..1....1..0..0..1....0..0..2..0 %e A204225 ..0..1..1..1....1..2..2..1....1..0..2..1....0..2..1..1....1..2..0..2 %e A204225 ..0..1..2..2....1..1..2..2....0..2..2..2....2..0..2..2....1..2..2..2 %e A204225 ..1..0..2..1....2..2..2..1....0..1..2..1....1..2..1..1....2..2..1..2 %K A204225 nonn %O A204225 1,1 %A A204225 _R. H. Hardin_ Jan 13 2012