login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A198802 Closed paths whose steps are roots of unity. Un(18) 0
1, 0, 18, 36, 918, 5400, 82800, 801360, 10907190, 132053040, 1802041668, 24199809480, 340640607384, 4834708246368, 70229958125184, 1032223723667136, 15391538570569590, 231935110984687968, 3531542904056225916, 54244559313713885688, 839979883121036697468 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Un(18), comment in article) : For each n >= 1, the sequence (Un(N))N >= 0 is P-recursive but is not algebraic when n > 2.

REFERENCES

Gilbert Labelle and Annie Lacasse, Closed paths whose steps are roots of unity, in FPSAC 2011, Reykjav┬┤k, Iceland DMTCS proc. AO, 2011, 599-610;

LINKS

Table of n, a(n) for n=0..20.

CROSSREFS

Sequence in context: A204824 A115550 A061713 * A041638 A041636 A212428

Adjacent sequences:  A198799 A198800 A198801 * A198803 A198804 A198805

KEYWORD

nonn

AUTHOR

Simon Plouffe, Oct 30 2011

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified November 21 11:17 EST 2014. Contains 249777 sequences.