A183942 Number of strings of n numbers x(i) in -7..7 with sums of x(i) and of x(i)*x(i+1) both zero

1, 1, 15, 57, 1033, 6259, 80851, 844829, 10894795, 130817901, 1781556515, 23640849007, 329173058411, 4518115025537, 63025886167079

Offset

1,3

Comments

Column 7 of A183944

Links

Table of n, a(n) for n=1..15.

Example

Some solutions for n=4
.-3....0....1...-7....0....2...-4....1...-6...-4....1....0....4....6....0....3
.-6...-1....0....0...-2....0....0....0....0....1....2...-4...-1....0....6....0
..6....0....0....0....0....0....4...-1....6....2...-2....0...-2....0....0....0
..3....1...-1....7....2...-2....0....0....0....1...-1....4...-1...-6...-6...-3

Crossrefs

Sequence in context: A084815 A240152 A261419 * A012691 A020187 A261798

Adjacent sequences: A183939 A183940 A183941 * A183943 A183944 A183945

Keyword

nonn

Author

R. H. Hardin Jan 08 2011

Status

approved