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A221622 Number of nX7 arrays with each row a permutation of 1..7 having at least as many downsteps as the preceding row 1
5040, 17052210, 49096652080, 130516916069715, 332469512259607296, 827196295133181978340, 2031241364747667201263520, 4951481629224145844957738085, 12021159412525485182456506260880 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A221623

LINKS

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

FORMULA

Empirical: a(n) = 5040*a(n-1) -8349390*a(n-2) +5234439280*a(n-3) -936232732785*a(n-4) +51206316902496*a(n-5) -99624831647040*a(n-6) +49349521382400*a(n-7)

EXAMPLE

Some solutions for n=3

..1..4..2..3..5..6..7....1..4..2..3..5..6..7....1..4..2..3..5..6..7

..2..1..3..7..6..4..5....2..1..3..5..4..6..7....2..1..3..6..7..5..4

..3..6..5..7..2..1..4....2..1..3..5..7..4..6....6..2..5..4..3..7..1

CROSSREFS

Sequence in context: A063411 A008552 A221437 * A318714 A227669 A010800

Adjacent sequences:  A221619 A221620 A221621 * A221623 A221624 A221625

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 21 2013

STATUS

approved

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Last modified May 28 15:33 EDT 2020. Contains 334684 sequences. (Running on oeis4.)