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

1,3

Comments

Column 5 of A225310

Links

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

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

Crossrefs

Sequence in context: A231298 A231359 A066757 * A331041 A317466 A045219

Adjacent sequences: A225303 A225304 A225305 * A225307 A225308 A225309

Keyword

nonn

Author

R. H. Hardin May 05 2013

Status

approved