cp's OEIS Frontend

A225307 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero and rows are nondecreasing (ways to put 6 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).

%I A225307 #6 Jun 02 2025 08:32:02
%S A225307 1,3,17,83,427,2341,13333,77721,461973,2791167,17087937,105766229,
%T A225307 660771733,4161393187,26390549923,168386196159,1080202503299,
%U A225307 6962854947491,45075011876699,292931328936351,1910374828122659
%N A225307 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero and rows are nondecreasing (ways to put 6 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 A225307 Column 6 of A225310
%H A225307 R. H. Hardin, <a href="/A225307/b225307.txt">Table of n, a(n) for n = 1..210</a>
%e A225307 Some solutions for n=4
%e A225307 .-1.-1.-1.-1..1..1...-1.-1.-1.-1..1..1....1..1..1..1..1..1...-1.-1.-1..1..1..1
%e A225307 ..1..1..1..1..1..1...-1.-1.-1.-1.-1..1...-1.-1.-1.-1.-1.-1...-1..1..1..1..1..1
%e A225307 .-1.-1..1..1..1..1...-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1.-1...-1.-1.-1..1..1..1
%e A225307 .-1.-1.-1.-1.-1..1...-1..1..1..1..1..1....1..1..1..1..1..1...-1.-1.-1.-1..1..1
%K A225307 nonn
%O A225307 1,2
%A A225307 _R. H. Hardin_ May 05 2013