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 A223993 #7 Jul 23 2025 04:47:27 %S A223993 3,31,476,7927,132119,2160036,34534687,540957770,8329684774, %T A223993 126518474741,1901584578700,28359907789963,420651674953990, %U A223993 6217185029060841,91703594406693983 %N A223993 Number of n X n 0..2 arrays with antidiagonals unimodal and rows and diagonals nondecreasing. %C A223993 Diagonal of A223999 %e A223993 Some solutions for n=3 %e A223993 ..0..0..1....0..1..2....0..0..2....1..2..2....0..1..1....0..0..0....0..2..2 %e A223993 ..0..0..1....0..0..1....0..1..1....0..1..2....0..1..1....0..1..2....0..0..2 %e A223993 ..0..1..1....0..1..2....0..1..1....1..1..1....0..2..2....1..2..2....0..1..1 %K A223993 nonn %O A223993 1,1 %A A223993 _R. H. Hardin_ Mar 30 2013