cp's OEIS Frontend

A225343 Number of nX7 -1,1 arrays such that the sum over i=1..n,j=1..7 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 7-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

%I A225343 #6 Jun 02 2025 08:33:11
%S A225343 0,0,0,22,0,0,0,25056,0,0,0,47084448,0,0,0,110202390974,0,0,0,
%T A225343 291612344834026,0,0,0,834664320724959518,0,0,0,
%U A225343 2522954614267660110474,0,0,0,7938386813443913197221460,0,0,0,25757964315025150183357153902,0,0,0
%N A225343 Number of nX7 -1,1 arrays such that the sum over i=1..n,j=1..7 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 7-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).
%C A225343 Column 7 of A225345
%H A225343 R. H. Hardin, <a href="/A225343/b225343.txt">Table of n, a(n) for n = 1..105</a>
%e A225343 Some solutions for n=4
%e A225343 .-1.-1.-1.-1..1..1..1...-1.-1..1..1..1..1..1...-1.-1.-1.-1.-1..1..1
%e A225343 .-1.-1.-1..1..1..1..1...-1.-1.-1.-1.-1..1..1...-1..1..1..1..1..1..1
%e A225343 .-1.-1.-1..1..1..1..1...-1.-1.-1.-1.-1..1..1...-1.-1.-1.-1..1..1..1
%e A225343 .-1.-1.-1.-1..1..1..1...-1.-1..1..1..1..1..1...-1.-1.-1.-1..1..1..1
%K A225343 nonn
%O A225343 1,4
%A A225343 _R. H. Hardin_ May 05 2013