A225344 - OEIS

%I #8 Oct 03 2025 23:43:59

%S 1,1,5,27,171,1081,7261,50659,364051,2676331,20044255,152452967,

%T 1174757541,9154016699,72023900129,571498084391,4568690484153,

%U 36765944370729,297627015600415,2422216988266317,19808260648181603

%N Number of nX8 -1,1 arrays such that the sum over i=1..n,j=1..8 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 8-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

%C Column 8 of A225345

%H R. H. Hardin, <a href="/A225344/b225344.txt">Table of n, a(n) for n = 1..97</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.-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..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..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.-1.-1..1..1

%K nonn

%O 1,3

%A _R. H. Hardin_, May 05 2013