A188355 Number of arrangements of n+1 numbers x(i) in -6..6 with the sum of x(i)*x(i+1) equal to zero.

25, 325, 1205, 14477, 100885, 1171345, 11535493, 136061137, 1540834589, 18592832393, 222616829157, 2732659664405, 33554957179729, 416689678586229, 5184974750699645, 64895937068447245, 813946908435419257

Offset

1,1

Comments

Column 6 of A188358.

Links

R. H. Hardin, Table of n, a(n) for n = 1..27

Example

Some solutions for n=4
..2...-3....1...-1...-6...-1....3...-6....1....2...-4...-3....1...-4....0...-2
..0...-2...-5....3...-2....0....5....1...-2...-1....0...-5....4...-1....1...-6
..6...-3...-1....3....6....2...-3....2...-3...-3...-5....3...-4....4....0...-1
..0....6....5....6...-6...-2....0....1....1...-1....4....0....6....0...-1....6
.-5....1....1...-4...-6...-2....4....2...-1....4....5...-3....6...-2....0...-2

Crossrefs

Cf. A188358.

Sequence in context: A000448 A000446 A124980 * A243089 A079875 A162702

Adjacent sequences: A188352 A188353 A188354 * A188356 A188357 A188358

Keyword

nonn

Author

R. H. Hardin, Mar 28 2011

Status

approved