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

1,2

Comments

Row 10 of A225345

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)

Example

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

Crossrefs

Sequence in context: A018237 A264270 A098256 * A171392 A105980 A031519

Adjacent sequences: A225347 A225348 A225349 * A225351 A225352 A225353

Keyword

nonn

Author

R. H. Hardin May 05 2013

Status

approved