A188256 Number of arrangements of 10 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero

0, 57808, 1657632, 20265640, 123729664, 591604824, 2026547348, 6250275112, 16132348896, 38938013924

Offset

1,2

Comments

Row 8 of A188249

Links

Table of n, a(n) for n=1..10.

Example

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

Crossrefs

Sequence in context: A166195 A031861 A119887 * A124729 A345565 A345820

Adjacent sequences: A188253 A188254 A188255 * A188257 A188258 A188259

Keyword

nonn

Author

R. H. Hardin Mar 25 2011

Status

approved