A225306 - OEIS

%I #4 May 05 2013 06:29:34

%S 0,0,12,52,0,0,5304,26498,0,0,3670280,19472528,0,0,3059952646,

%T 16735288748,0,0,2821236602612,15715467775786,0,0,2770728141476684,

%U 15624859528160442,0,0,2841704521905480868,16166720093745817028,0,0

%N 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)

%C Column 5 of A225310

%H R. H. Hardin, <a href="/A225306/b225306.txt">Table of n, a(n) for n = 1..210</a>

%e Some solutions for n=4

%e ..1..1..1..1..1...-1.-1.-1..1..1...-1.-1.-1..1..1....1..1..1..1..1

%e .-1.-1.-1.-1.-1...-1.-1.-1..1..1...-1..1..1..1..1...-1..1..1..1..1

%e .-1.-1.-1.-1.-1....1..1..1..1..1....1..1..1..1..1...-1.-1.-1.-1.-1

%e ..1..1..1..1..1...-1.-1.-1.-1..1...-1.-1.-1.-1.-1...-1.-1..1..1..1

%K nonn

%O 1,3

%A _R. H. Hardin_ May 05 2013