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 A200987 #7 Jul 22 2025 16:02:59 %S A200987 1,21,140,1095,4919,27000,97341,383172,1188521,3704820,9947816, %T A200987 27240277,65292069,157646021,349738426,770969390,1585648871, %U A200987 3256248216,6303135880,12177430692,22459794938,41128002746,72582886199,127586136583 %N A200987 Number of nX5 0..4 arrays with every row and column nondecreasing rightwards and downwards, and the number of instances of each value within one of each other. %C A200987 Column 5 of A200990 %H A200987 R. H. Hardin, <a href="/A200987/b200987.txt">Table of n, a(n) for n = 1..32</a> %e A200987 Some solutions for n=3 %e A200987 ..0..0..0..2..4....0..0..1..1..1....0..0..1..1..1....0..0..1..1..4 %e A200987 ..1..1..1..3..4....0..2..2..2..4....0..2..2..2..3....0..2..2..2..4 %e A200987 ..2..2..3..3..4....3..3..3..4..4....3..3..4..4..4....1..3..3..3..4 %K A200987 nonn %O A200987 1,2 %A A200987 _R. H. Hardin_ Nov 25 2011