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A215289 Number of permutations of 0..floor((n*5-1)/2) on even squares of an nX5 array such that each row and column of even squares is increasing 1
1, 10, 140, 2100, 60060, 1051050, 42882840, 814773960, 41227562376, 824551247520, 48236247979920, 999179422441200, 64899082486180800, 1379105502831342000, 96951116849043342600, 2100607531729272423000, 157112712418611824074200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 5 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(3,f3)*A060854(2,f4)*binomial(3*f3+2*f4,3*f3)

EXAMPLE

Some solutions for n=5

..0..x..2..x..6....1..x..2..x..6....0..x..3..x..9....0..x..1..x..8

..x..3..x..4..x....x..0..x..4..x....x..2..x..4..x....x..3..x..6..x

..1..x..7..x.10....7..x..9..x.11....1..x..7..x.11....2..x..4..x..9

..x..5..x.11..x....x..3..x..5..x....x..5..x..8..x....x..7..x.10..x

..8..x..9..x.12....8..x.10..x.12....6..x.10..x.12....5..x.11..x.12

CROSSREFS

Sequence in context: A089834 A132505 A254336 * A319578 A051618 A295034

Adjacent sequences:  A215286 A215287 A215288 * A215290 A215291 A215292

KEYWORD

nonn

AUTHOR

R. H. Hardin Aug 07 2012

STATUS

approved

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Last modified December 7 20:19 EST 2021. Contains 349588 sequences. (Running on oeis4.)