A208938 Number of n-bead necklaces labeled with numbers -1..1 not allowing reversal, with sum zero with no three beads in a row equal.

1, 2, 2, 5, 8, 20, 38, 88, 196, 464, 1088, 2628, 6344, 15554, 38318, 95170, 237536, 596286, 1503098, 3805452, 9668776, 24650428, 63035390, 161648194, 415589336, 1071003162, 2766083600, 7158525512, 18561001524, 48210881198, 125430649666

Offset

1,2

Comments

Column 1 of A208945.

Links

R. H. Hardin, Table of n, a(n) for n = 1..33

Example

All solutions for n=5:
.-1...-1...-1...-1...-1...-1...-1...-1
..0....0....0....0...-1....1...-1...-1
.-1....1....0....1....1...-1....0....1
..1....0....1...-1....1....1....1....0
..1....0....0....1....0....0....1....1

Crossrefs

Sequence in context: A095005 A209066 A344036 * A019086 A076949 A040009

Adjacent sequences: A208935 A208936 A208937 * A208939 A208940 A208941

Keyword

nonn

Author

R. H. Hardin, Mar 03 2012

Status

approved