A188364 Number of arrangements of 9 numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero

4671, 173409, 1763151, 10396729, 40629247, 136061137, 355442823, 870473329, 1876439327, 3821007601, 7047842559

Offset

1,1

Comments

Row 8 of A188358

Links

Table of n, a(n) for n=1..11.

Example

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

Crossrefs

Sequence in context: A062626 A204489 A252127 * A236014 A202431 A066731

Adjacent sequences: A188361 A188362 A188363 * A188365 A188366 A188367

Keyword

nonn

Author

R. H. Hardin Mar 28 2011

Status

approved