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 A223858 #7 Jul 23 2025 04:35:49 %S A223858 4,100,4884,315124,23738426,1989679315,181330154458,17720685250743, %T A223858 1838270364212150,200766237618388230,22925992371163981667, %U A223858 2721355255765297425689 %N A223858 Number of n X n 0..3 arrays with rows and antidiagonals unimodal and columns nondecreasing. %C A223858 Diagonal of A223864 %e A223858 Some solutions for n=3 %e A223858 ..0..1..2....0..0..2....0..0..1....1..0..0....3..0..0....0..1..3....0..1..1 %e A223858 ..0..1..2....1..1..3....1..1..2....2..0..0....3..3..0....0..2..3....0..1..1 %e A223858 ..0..3..2....1..2..3....1..3..2....3..2..2....3..3..0....0..2..3....3..3..3 %K A223858 nonn %O A223858 1,1 %A A223858 _R. H. Hardin_ Mar 28 2013