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A225342 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 6-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship) 1
1, 1, 3, 17, 81, 397, 2073, 11291, 63121, 360909, 2102597, 12439855, 74561687, 451920441, 2765717847, 17069622035, 106139191511, 664358517275, 4183117802521, 26479526009223, 168426949915891, 1076002461947039 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 6 of A225345

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..112

EXAMPLE

Some solutions for n=4

.-1.-1.-1..1..1..1...-1.-1.-1..1..1..1...-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1..1

.-1.-1.-1.-1..1..1...-1.-1..1..1..1..1...-1..1..1..1..1..1...-1..1..1..1..1..1

.-1..1..1..1..1..1...-1.-1.-1.-1.-1..1...-1.-1.-1.-1..1..1...-1..1..1..1..1..1

.-1.-1.-1.-1..1..1...-1.-1..1..1..1..1...-1.-1.-1..1..1..1...-1.-1.-1.-1.-1..1

CROSSREFS

Sequence in context: A093568 A164305 A202247 * A194596 A217623 A083217

Adjacent sequences:  A225339 A225340 A225341 * A225343 A225344 A225345

KEYWORD

nonn

AUTHOR

R. H. Hardin May 05 2013

STATUS

approved

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Last modified February 29 09:35 EST 2020. Contains 332355 sequences. (Running on oeis4.)