A225306 Number of nX5 -1,1 arrays such that the sum over i=1..n,j=1..5 of i*x(i,j) is zero and rows are nondecreasing (ways to put 5 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

0, 0, 12, 52, 0, 0, 5304, 26498, 0, 0, 3670280, 19472528, 0, 0, 3059952646, 16735288748, 0, 0, 2821236602612, 15715467775786, 0, 0, 2770728141476684, 15624859528160442, 0, 0, 2841704521905480868, 16166720093745817028, 0, 0

Offset: 1

Author

R. H. Hardin May 05 2013

Keywords

• nonn

Comments

Column 5 of A225310

Examples

			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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210