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 A212937 #8 Mar 27 2023 15:42:24 %S A212937 1,7,9019,2509306671,212180664326328751,8389667096561737605103329223, %T A212937 227328735342370296661661894900118524516359, %U A212937 5846438367263951495694598571033398108516477233229168235359 %N A212937 Number of n X n 0..n-1 arrays with no column j greater than or equal to than column j-1 in all rows. %C A212937 Diagonal of A212943. %H A212937 R. H. Hardin, <a href="/A212937/b212937.txt">Table of n, a(n) for n = 1..17</a> %e A212937 Some solutions for n=4 %e A212937 ..1..3..0..1....1..3..2..1....2..1..1..1....3..3..2..1....0..0..0..3 %e A212937 ..0..0..1..0....1..1..0..3....0..2..1..3....3..2..2..2....0..1..1..2 %e A212937 ..0..1..1..3....2..3..3..0....3..1..2..0....2..3..2..2....0..2..2..1 %e A212937 ..3..0..3..1....1..0..3..0....2..2..1..2....3..1..1..2....2..1..0..2 %Y A212937 Cf. A212943. %K A212937 nonn %O A212937 1,2 %A A212937 _R. H. Hardin_, May 31 2012