A183936 Number of strings of n numbers x(i) in -1..1 with sums of x(i) and of x(i)*x(i+1) both zero

1, 1, 3, 7, 21, 45, 121, 261, 723, 1723, 5087, 13091, 38641, 101993, 297423, 800187, 2324961, 6378601, 18544345, 51670725, 150172263, 422922591, 1228542913, 3488055573, 10134018375, 28962183951, 84203226523, 241924870591

Offset

1,3

Comments

Column 1 of A183944

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Example

All solutions for n=4
..1....0....0...-1...-1....1....0
..0....0....1....0....0....0...-1
.-1....0....0....0....1....0....0
..0....0...-1....1....0...-1....1

Crossrefs

Sequence in context: A119959 A329114 A018712 * A027151 A219589 A092203

Adjacent sequences: A183933 A183934 A183935 * A183937 A183938 A183939

Keyword

nonn

Author

R. H. Hardin Jan 08 2011

Status

approved