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A215291 Number of permutations of 0..floor((n*7-1)/2) on even squares of an nX7 array such that each row and column of even squares is increasing 1
1, 35, 2310, 210210, 42882840, 5703417720, 2061378118800, 337653735859440, 173457547735792320, 32436561426593163840, 21174123919831066023840, 4340695403565368534887200, 3373030378241974592216989200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A215292

LINKS

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

FORMULA

f3=floor((n+1)/2)

f4=floor(n/2)

a(n) = A060854(4,f3)*A060854(3,f4)*binomial(4*f3+3*f4,4*f3)

EXAMPLE

Some solutions for n=3

..0..x..3..x..5..x..6....0..x..1..x..2..x..3....1..x..2..x..3..x..5

..x..1..x..8..x.10..x....x..5..x..8..x.10..x....x..0..x..6..x.10..x

..2..x..4..x..7..x..9....4..x..6..x..7..x..9....4..x..7..x..8..x..9

CROSSREFS

Sequence in context: A001825 A094187 A202921 * A249886 A290584 A174749

Adjacent sequences:  A215288 A215289 A215290 * A215292 A215293 A215294

KEYWORD

nonn

AUTHOR

R. H. Hardin Aug 07 2012

STATUS

approved

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Last modified November 29 18:41 EST 2021. Contains 349416 sequences. (Running on oeis4.)