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

1,4

Comments

Column 3 of A225345

Links

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

Example

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

Crossrefs

Sequence in context: A028599 A270850 A322379 * A365989 A365990 A354883

Adjacent sequences: A225336 A225337 A225338 * A225340 A225341 A225342

Keyword

nonn

Author

R. H. Hardin May 05 2013

Status

approved