A183938 Number of strings of n numbers x(i) in -3..3 with sums of x(i) and of x(i)*x(i+1) both zero

1, 1, 7, 21, 169, 635, 3803, 19013, 115755, 642065, 4138291, 25416351, 165975915, 1053686983, 6884578761, 44272817075, 290607235917, 1898355935879, 12584064113799, 83219457433335, 554858908945825, 3692717431924057

Offset

1,3

Comments

Column 3 of A183944

Links

R. H. Hardin, Table of n, a(n) for n = 1..41

Example

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

Crossrefs

Sequence in context: A267609 A032032 A084711 * A060146 A357673 A111878

Adjacent sequences: A183935 A183936 A183937 * A183939 A183940 A183941

Keyword

nonn

Author

R. H. Hardin Jan 08 2011

Status

approved