A208964 Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero and first and second differences in -2..2.

1, 1, 1, 3, 3, 8, 15, 42, 94, 246, 613, 1645, 4361, 11980, 33023, 92484, 259762, 735310, 2088403, 5961138, 17070131, 49059542, 141402328, 408736264, 1184435227, 3440434897, 10014880408, 29211476668, 85362417183, 249882401380, 732670159161, 2151506490430

Offset

1,4

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Example

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

Crossrefs

Column 2 of A208970.

Sequence in context: A055057 A154029 A219349 * A104864 A300367 A296106

Adjacent sequences: A208961 A208962 A208963 * A208965 A208966 A208967

Keyword

nonn

Author

R. H. Hardin, Mar 03 2012

Extensions

a(23)-a(32) from Andrew Howroyd, Mar 12 2017

Status

approved