The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A209025 Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and first differences in -1..1. 1
1, 1, 1, 2, 2, 4, 6, 13, 21, 45, 83, 181, 362, 794, 1676, 3703, 8049, 17925, 39679, 88980, 199308, 449714, 1015574, 2303940, 5234731, 11931095, 27239911, 62337821, 142894336, 328168558, 754815704, 1738888333, 4011453913, 9266702091, 21433240903, 49633242760 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
EXAMPLE
All solutions for n=6:
..0...-1...-1...-1
..0....0...-1....0
..0....0....0....0
..0....1....1....0
..0....0....1....1
..0....0....0....0
CROSSREFS
Column 1 of A209032.
Sequence in context: A282164 A268175 A363578 * A346779 A153955 A074028
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 04 2012
EXTENSIONS
a(33)-a(36) from Andrew Howroyd, Mar 19 2017
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 17 00:51 EDT 2024. Contains 373432 sequences. (Running on oeis4.)