A225339 Number of nX3 -1,1 arrays such that the sum over i=1..n,j=1..3 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 3-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

0, 0, 0, 6, 0, 0, 0, 410, 0, 0, 0, 47990, 0, 0, 0, 7030132, 0, 0, 0, 1163743294, 0, 0, 0, 208310242542, 0, 0, 0, 39371238885750, 0, 0, 0, 7745062224896578, 0, 0, 0, 1571069270148096124, 0, 0, 0, 326518765865030556374, 0, 0, 0

Offset: 1

Author

R. H. Hardin May 05 2013

Keywords

• nonn

Comments

Column 3 of A225345

Examples

			All 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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..159