login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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
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: A052531 A257517 A095005 * A208938 A019086 A076949

Adjacent sequences:  A209063 A209064 A209065 * A209067 A209068 A209069

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 04 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 27 21:52 EDT 2020. Contains 334671 sequences. (Running on oeis4.)