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 A212933 #6 Jul 22 2025 22:59:27 %S A212933 1,255,518320,4041974015,85800824609376,4051316109991426752, %T A212933 372271852759802667094256,60525940157456181486116315391, %U A212933 16213293097463939456656505907266320 %N A212933 Number of 4Xn 0..n-1 arrays with no column j greater than column j-1 in all rows. %C A212933 Row 4 of A212930 %H A212933 R. H. Hardin, <a href="/A212933/b212933.txt">Table of n, a(n) for n = 1..16</a> %e A212933 Some solutions for n=3 %e A212933 ..2..0..1....2..1..0....0..0..2....0..0..0....2..2..2....2..2..1....2..2..0 %e A212933 ..0..0..2....2..1..2....0..0..2....2..0..2....1..2..1....2..0..0....0..0..2 %e A212933 ..1..1..2....2..1..1....0..0..0....2..0..1....0..2..2....2..0..0....2..0..0 %e A212933 ..0..0..0....0..1..1....1..2..0....0..0..0....0..0..2....2..2..2....1..0..1 %K A212933 nonn %O A212933 1,2 %A A212933 _R. H. Hardin_ May 31 2012