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 A221628 #6 Jul 23 2025 02:04:20 %S A221628 1,7,7279,14576404,230141263315,7575106427737240, %T A221628 827196295133181978340,177037611175595181692394660, %U A221628 86030164534670200470739520304375,75149351745335662460465241596540458600 %N A221628 Number of 6Xn arrays with each row a permutation of 1..n having at least as many downsteps as the preceding row. %C A221628 Row 6 of A221623 %H A221628 R. H. Hardin, <a href="/A221628/b221628.txt">Table of n, a(n) for n = 1..13</a> %e A221628 Some solutions for n=3 %e A221628 ..2..3..1....1..2..3....1..3..2....1..3..2....3..1..2....1..3..2....3..1..2 %e A221628 ..1..3..2....1..2..3....2..1..3....1..3..2....3..1..2....2..3..1....1..3..2 %e A221628 ..3..1..2....2..1..3....2..3..1....2..3..1....1..3..2....2..1..3....2..1..3 %e A221628 ..1..3..2....2..3..1....2..1..3....2..3..1....1..3..2....3..1..2....2..1..3 %e A221628 ..2..3..1....3..1..2....1..3..2....3..1..2....2..1..3....2..3..1....2..1..3 %e A221628 ..3..1..2....2..3..1....2..3..1....2..3..1....2..3..1....1..3..2....3..2..1 %K A221628 nonn %O A221628 1,2 %A A221628 _R. H. Hardin_ Jan 21 2013