cp's OEIS Frontend

A221621 Number of nX6 arrays with each row a permutation of 1..6 having at least as many downsteps as the preceding row.

%I A221621 #6 Jul 23 2025 02:03:32
%S A221621 720,353654,148700748,57614883627,21241004664348,7575106427737240,
%T A221621 2638115823321645192,902542985526634773509,304529313276100670030616,
%U A221621 101620178879261858322711162,33604296810830843896378600020
%N A221621 Number of nX6 arrays with each row a permutation of 1..6 having at least as many downsteps as the preceding row.
%C A221621 Column 6 of A221623
%H A221621 R. H. Hardin, <a href="/A221621/b221621.txt">Table of n, a(n) for n = 1..210</a>
%F A221621 Empirical: a(n) = 720*a(n-1) -164746*a(n-2) +12686988*a(n-3) -321204409*a(n-4) +605003244*a(n-5) -296321796*a(n-6)
%e A221621 Some solutions for n=3
%e A221621 ..4..1..2..5..3..6....4..1..2..5..3..6....4..1..2..5..3..6....4..1..2..5..3..6
%e A221621 ..1..4..6..3..5..2....3..1..2..5..4..6....4..1..2..6..5..3....3..1..5..4..6..2
%e A221621 ..2..1..4..3..6..5....3..6..2..5..4..1....5..4..6..3..1..2....2..1..4..3..6..5
%K A221621 nonn
%O A221621 1,1
%A A221621 _R. H. Hardin_ Jan 21 2013