A189946 1/4 the number of arrangements of n+1 nonzero numbers x(i) in -4..4 with the sum of sign(x(i))*(|x(i)| mod x(i+1)) equal to zero.

8, 29, 159, 1246, 9884, 73992, 542353, 4014514, 30195535, 229483051, 1753032755, 13435104833, 103277494510, 796249956004, 6155156882177, 47687937106356, 370185895527595, 2878540976279306, 22417566580905998, 174824418896006501

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Example

Some solutions with n=3
..1....3...-4....2...-2...-1....4...-1....2....4...-3....1....1....4...-4...-1
.-1....1....4....2...-1....3...-2...-3....2...-4....2...-2....3...-2....3....3
.-1...-4....4....1...-1....2....1....3....2....2....1...-1...-2....2....3....1
..1...-3....2....1...-1...-1....1....2...-2....1....4...-2....4....1....2...-2

Crossrefs

Column 4 of A189951.

Sequence in context: A088131 A072264 A110527 * A239855 A239029 A071931

Adjacent sequences: A189943 A189944 A189945 * A189947 A189948 A189949

Keyword

nonn

Author

R. H. Hardin, May 02 2011

Status

approved