A209066 - OEIS

A209066

Number of n-bead necklaces labeled with numbers -1..1 not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.

1, 2, 2, 5, 8, 19, 39, 95, 223, 554, 1373, 3493, 8906, 23016, 59805, 156588, 412082, 1090443, 2897828, 7733433, 20712345, 55661171, 150031505, 405533996, 1098949141, 2985066757, 8125987470, 22165517960, 60575472281, 165835969094

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Column 1 of A209073.

LINKS

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

EXAMPLE

Some solutions for n=6:

.-1...-1...-1...-1....0...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1

..1....0...-1...-1....0...-1....0....1....0...-1....1....0....1....0...-1....0

..0...-1....1....1....0....0....0...-1...-1....1....0....0...-1....0....1....0

.-1....1....0...-1....0....0....1....1....1....0....0....0....1....1....1...-1

..1....0....0....1....0....1...-1...-1....1....1....0....1....0....0...-1....1

..0....1....1....1....0....1....1....1....0....0....0....0....0....0....1....1

CROSSREFS

Sequence in context: A257517 A337079 A095005 * A344036 A208938 A019086

Adjacent sequences: A209063 A209064 A209065 * A209067 A209068 A209069

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 04 2012

STATUS

approved