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 A223832 #13 Mar 18 2025 17:08:29 %S A223832 1,2,9,48,249,1240,5992,28369,132427,611901,2805670,12786249,57979474, %T A223832 261797013,1177774158,5281497918 %N A223832 Number of n X n 0..1 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing. %e A223832 Some solutions for n=3: %e A223832 ..0..1..0....0..0..0....1..1..0....0..0..1....0..0..0....1..1..1....0..0..0 %e A223832 ..0..1..1....1..0..0....1..1..0....0..0..1....0..1..0....1..1..1....0..1..0 %e A223832 ..1..1..1....1..1..1....1..1..1....0..1..1....0..1..0....1..1..1....0..1..1 %Y A223832 Main diagonal of A223838. %K A223832 nonn,more %O A223832 0,2 %A A223832 _R. H. Hardin_, Mar 27 2013 %E A223832 a(0)=1 prepended by _Alois P. Heinz_, Feb 14 2024 %E A223832 Name corrected by _Andrew Howroyd_, Mar 18 2025