cp's OEIS Frontend

A225342 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 6-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

%I A225342 #6 Jun 02 2025 08:33:05
%S A225342 1,1,3,17,81,397,2073,11291,63121,360909,2102597,12439855,74561687,
%T A225342 451920441,2765717847,17069622035,106139191511,664358517275,
%U A225342 4183117802521,26479526009223,168426949915891,1076002461947039
%N A225342 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 6-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).
%C A225342 Column 6 of A225345
%H A225342 R. H. Hardin, <a href="/A225342/b225342.txt">Table of n, a(n) for n = 1..112</a>
%e A225342 Some solutions for n=4
%e A225342 .-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 A225342 .-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 A225342 .-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 A225342 .-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 A225342 nonn
%O A225342 1,3
%A A225342 _R. H. Hardin_ May 05 2013