%I #4 May 05 2013 06:28:36
%S 1,3,9,31,113,443,1787,7445,31593,136351,596187,2636015,11763569,
%T 52920569,239731317,1092632909,5006816043,23053197067,106601983853,
%U 494856940025,2305237337415,10772988573393,50491926308985
%N Number of nX4 1,1 arrays such that the sum over i=1..n,j=1..4 of i*x(i,j) is zero and rows are nondecreasing (ways to put 4 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a southpointing gate without turning the gate)
%C Column 4 of A225310
%H R. H. Hardin, <a href="/A225305/b225305.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 1,2
%A _R. H. Hardin_ May 05 2013
