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 A250680 #6 Jul 23 2025 12:40:56 %S A250680 11736,210158,3107446,41503790,505108522,5726252240,61498698426, %T A250680 632850763138,6297768773474,61000028098516,578059653008102, %U A250680 5380105017634102,49331581021446126,446710039295094002 %N A250680 Number of (4+1)X(n+1) 0..3 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction. %C A250680 Row 4 of A250676 %H A250680 R. H. Hardin, <a href="/A250680/b250680.txt">Table of n, a(n) for n = 1..210</a> %e A250680 Some solutions for n=1 %e A250680 ..2..0....2..1....1..2....3..0....2..0....0..2....1..2....0..2....1..1....0..3 %e A250680 ..0..2....3..0....3..0....3..0....2..1....0..2....3..0....2..0....2..0....1..2 %e A250680 ..2..0....3..0....1..2....3..0....2..2....0..2....1..2....2..1....2..2....1..2 %e A250680 ..1..3....3..0....2..1....2..1....2..3....0..2....2..1....2..1....1..3....2..1 %e A250680 ..3..1....3..0....3..0....1..3....3..2....1..1....2..3....2..2....2..2....0..3 %K A250680 nonn %O A250680 1,1 %A A250680 _R. H. Hardin_, Nov 26 2014