A188254 Number of arrangements of 8 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero

0, 4132, 51196, 368588, 1399640, 4875112, 11953848, 28779900, 58731504, 116157280, 200181920, 362242468, 569517636

Offset

1,2

Comments

Row 6 of A188249

Links

Table of n, a(n) for n=1..13.

Example

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

Crossrefs

Sequence in context: A117810 A236871 A300194 * A162003 A346901 A346885

Adjacent sequences: A188251 A188252 A188253 * A188255 A188256 A188257

Keyword

nonn

Author

R. H. Hardin Mar 25 2011

Status

approved