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A130978 G.f.: 12/(5+7*sqrt(1-24*x)). 6
1, 7, 91, 1435, 24955, 460747, 8859739, 175466347, 3553964155, 73266506635, 1532152991131, 32420721097387, 692865048943291, 14932919812627915, 324195908270339035, 7083228794200550635 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of walks of length 2n on the 7-regular tree beginning and ending at some fixed vertex. Hankel transform is A135314. - Philippe Deléham, Feb 25 2009

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

FORMULA

a(n) = Sum{k, 0<=k<=n}A039599(n,k)*6^(n-k). - Philippe Deléham, Aug 25 2007

Recurrence: n*a(n) = (73*n-36)*a(n-1) - 588*(2*n-3)*a(n-2) . - Vaclav Kotesovec, Oct 20 2012

a(n) ~ 7*2^(3*n+1)*3^(n+1)/(25*sqrt(Pi)*n^(3/2)) . - Vaclav Kotesovec, Oct 20 2012

MAPLE

g:=12/(5+7*sqrt(1-24*x)); gser:=series(g, x=0, 20); seq(coeff(gser, x, n), n=0..15); - Emeric Deutsch, Aug 26 2007

MATHEMATICA

CoefficientList[Series[12/(5+7*Sqrt[1-24*x]), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 20 2012 *)

CROSSREFS

Column k=7 of A183135.

Sequence in context: A156712 A004368 A243946 * A191097 A234570 A133307

Adjacent sequences:  A130975 A130976 A130977 * A130979 A130980 A130981

KEYWORD

nonn

AUTHOR

Philippe Deléham, Aug 23 2007

EXTENSIONS

More terms from Emeric Deutsch, Aug 26 2007

STATUS

approved

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Last modified February 19 10:40 EST 2018. Contains 299330 sequences. (Running on oeis4.)