cp's OEIS Frontend

A225341 Number of nX5 -1,1 arrays such that the sum over i=1..n,j=1..5 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 5-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

%I A225341 #6 Jun 02 2025 08:32:57
%S A225341 0,0,0,12,0,0,0,4508,0,0,0,2680534,0,0,0,1985837462,0,0,0,
%T A225341 1663045511892,0,0,0,1506336601246000,0,0,0,1440828827246863370,0,0,0,
%U A225341 1434551060282150636452,0,0,0,1472882578482323918604276,0,0,0
%N A225341 Number of nX5 -1,1 arrays such that the sum over i=1..n,j=1..5 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 5-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).
%C A225341 Column 5 of A225345
%H A225341 R. H. Hardin, <a href="/A225341/b225341.txt">Table of n, a(n) for n = 1..123</a>
%e A225341 Some solutions for n=4
%e A225341 .-1.-1.-1.-1..1...-1.-1.-1.-1.-1....1..1..1..1..1...-1.-1.-1..1..1
%e A225341 .-1..1..1..1..1....1..1..1..1..1...-1.-1.-1.-1.-1...-1..1..1..1..1
%e A225341 .-1..1..1..1..1....1..1..1..1..1...-1.-1.-1.-1.-1...-1.-1.-1.-1..1
%e A225341 .-1.-1.-1.-1..1...-1.-1.-1.-1.-1....1..1..1..1..1...-1.-1..1..1..1
%K A225341 nonn
%O A225341 1,4
%A A225341 _R. H. Hardin_ May 05 2013