A225350 Number of 10Xn -1,1 arrays such that the sum over i=1..10,j=1..n of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute n-across galley oarsmen left-right at 10 fore-aft positions so that there are no turning moments on the ship).

0, 443, 0, 24893, 0, 360909, 0, 2676331, 0, 13280209, 0, 50435657, 0, 158259755, 0, 430394067, 0, 1047240813, 0, 2331232209, 0, 4825180007, 0, 9399464741, 0, 17394354077, 0, 30804515135, 0, 52513235123, 0, 86584738985, 0, 138623327831, 0

Offset: 1

Author

R. H. Hardin May 05 2013

Keywords

• nonn

Comments

Row 10 of A225345

Examples

			Some solutions for n=4
..1..1..1..1...-1.-1.-1.-1...-1.-1.-1..1...-1.-1.-1..1...-1.-1.-1.-1
.-1.-1.-1.-1....1..1..1..1...-1..1..1..1...-1..1..1..1...-1..1..1..1
.-1.-1.-1..1...-1.-1.-1.-1...-1..1..1..1...-1.-1.-1..1...-1.-1..1..1
.-1..1..1..1....1..1..1..1...-1.-1.-1..1...-1.-1..1..1....1..1..1..1
..1..1..1..1....1..1..1..1...-1.-1..1..1...-1..1..1..1...-1..1..1..1
.-1.-1.-1.-1...-1..1..1..1...-1.-1..1..1...-1..1..1..1...-1.-1.-1.-1
.-1.-1.-1..1...-1.-1.-1.-1...-1..1..1..1...-1..1..1..1...-1.-1.-1..1
.-1.-1.-1..1...-1.-1.-1..1...-1.-1.-1..1...-1.-1.-1..1....1..1..1..1
..1..1..1..1...-1.-1.-1.-1...-1.-1.-1..1...-1.-1.-1.-1...-1.-1..1..1
.-1.-1..1..1....1..1..1..1...-1..1..1..1...-1..1..1..1...-1.-1.-1..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = a(n-2) +a(n-4) -a(n-10) -a(n-14) -a(n-20) +2*a(n-24) +a(n-26) +a(n-28) +a(n-30) -a(n-34) -a(n-36) -a(n-38) -2*a(n-40) -a(n-42) -a(n-44) +a(n-46) +a(n-48) +2*a(n-50) +a(n-52) +a(n-54) +a(n-56) -a(n-60) -a(n-62) -a(n-64) -2*a(n-66) +a(n-70) +a(n-76) +a(n-80) -a(n-86) -a(n-88) +a(n-90)