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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130980 G.f.: 16/(7 + 9*sqrt(1 - 32*x)). 6
1, 9, 153, 3177, 73017, 1785609, 45543897, 1197639081, 32231934585, 883404542025, 24570973169433, 691759954058985, 19674867844155321, 564462038150345097, 16315646312285498457, 474680922491822688297 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of walks of length 2n on the 9-regular tree beginning and ending at some fixed vertex. Hankel transform is A135320. - Philippe Deléham, Feb 25 2009

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..660

FORMULA

a(n) = Sum_{k=0..n} A039599(n,k)*8^(n-k). - Philippe Deléham, Aug 25 2007

a(n) ~ 72/49*32^n/(sqrt(Pi)*n^(3/2)). - Vaclav Kotesovec, Jun 29 2013

MATHEMATICA

CoefficientList[Series[16/(7+9*Sqrt[1-32*x]), {x, 0, 30}], x] (* Harvey P. Dale, Feb 21 2013 *)

PROG

(PARI) Vec(16/(7 + 9*sqrt(1-32*x)) + O(x^50)) \\ G. C. Greubel, Jan 28 2017

CROSSREFS

Column k=9 of A183135.

Sequence in context: A246641 A169958 A012017 * A133309 A228713 A151835

Adjacent sequences:  A130977 A130978 A130979 * A130981 A130982 A130983

KEYWORD

nonn

AUTHOR

Philippe Deléham, Aug 23 2007

EXTENSIONS

More terms from Olivier Gérard, Sep 22 2007

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 23 01:57 EDT 2018. Contains 316518 sequences. (Running on oeis4.)