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

720, 353654, 148700748, 57614883627, 21241004664348, 7575106427737240, 2638115823321645192, 902542985526634773509, 304529313276100670030616, 101620178879261858322711162, 33604296810830843896378600020

Offset: 1

Author

R. H. Hardin Jan 21 2013

Keywords

• nonn

Comments

Column 6 of A221623

Examples

			Some solutions for n=3
..4..1..2..5..3..6....4..1..2..5..3..6....4..1..2..5..3..6....4..1..2..5..3..6
..1..4..6..3..5..2....3..1..2..5..4..6....4..1..2..6..5..3....3..1..5..4..6..2
..2..1..4..3..6..5....3..6..2..5..4..1....5..4..6..3..1..2....2..1..4..3..6..5
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 720*a(n-1) -164746*a(n-2) [phone]*a(n-3) -321204409*a(n-4) [phone]*a(n-5) -296321796*a(n-6)