OFFSET
0,2
COMMENTS
Number of walks of length 2n on the 8-regular tree beginning and ending at some fixed vertex. Hankel transform is A135315. - Philippe Deléham, Feb 25 2009
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..690
FORMULA
a(n) = Sum_{k=0..n} A039599(n,k)*7^(n-k). - Philippe Deléham, Aug 25 2007
a(n) ~ 14*28^n/(9*sqrt(Pi)*n^(3/2)). - Vaclav Kotesovec, Jun 29 2013
D-finite with recurrence: n*a(n) +2*(-46*n+21)*a(n-1) +896*(2*n-3)*a(n-2)=0. - R. J. Mathar, Jan 20 2020
MATHEMATICA
CoefficientList[Series[7/(3 + 4*Sqrt[1 - 28*x]), {x, 0, 50}], x] (* G. C. Greubel, Jan 28 2017 *)
PROG
(PARI) Vec(7/(3 + 4*sqrt(1-28*x)) + O(x^50)) \\ G. C. Greubel, Jan 28 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Philippe Deléham, Aug 23 2007
EXTENSIONS
More terms from Olivier Gérard, Sep 22 2007
STATUS
approved