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A225343
Number of nX7 -1,1 arrays such that the sum over i=1..n,j=1..7 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 7-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship)
1
0, 0, 0, 22, 0, 0, 0, 25056, 0, 0, 0, 47084448, 0, 0, 0, 110202390974, 0, 0, 0, 291612344834026, 0, 0, 0, 834664320724959518, 0, 0, 0, 2522954614267660110474, 0, 0, 0, 7938386813443913197221460, 0, 0, 0, 25757964315025150183357153902, 0, 0, 0
OFFSET
1,4
COMMENTS
Column 7 of A225345
LINKS
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
CROSSREFS
Sequence in context: A104787 A023922 A022064 * A252670 A297813 A156462
KEYWORD
nonn
AUTHOR
R. H. Hardin May 05 2013
STATUS
approved