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 A250776 #6 Jul 23 2025 12:45:42 %S A250776 9,46,230,1152,5688,27986,137082,670608,3275574,15987988,77980390, %T A250776 380145754,1852275976,9021572492,43923360572,213777365336 %N A250776 Number of (n+1)X(n+1) 0..1 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 A250776 Diagonal of A250783 %e A250776 Some solutions for n=4 %e A250776 ..1..0..0..0..0....1..0..0..0..1....1..0..1..0..1....0..1..0..0..1 %e A250776 ..1..0..0..0..0....1..0..0..0..1....1..0..1..0..1....0..1..0..0..1 %e A250776 ..1..0..0..0..1....1..0..0..0..1....1..0..1..0..1....0..1..0..0..1 %e A250776 ..0..1..1..1..0....1..1..1..1..0....0..1..0..1..0....0..1..0..1..0 %e A250776 ..0..1..1..1..0....1..1..1..1..1....0..1..0..1..1....0..1..1..0..1 %K A250776 nonn %O A250776 1,1 %A A250776 _R. H. Hardin_, Nov 27 2014