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A026857 a(n) = T(2n+1,n+4), T given by A026736. 1
1, 9, 55, 287, 1381, 6343, 28313, 124083, 537242, 2307118, 9852240, 41910428, 177807902, 752981956, 3184773246, 13459063660, 56849094136, 240047748038, 1013452871316, 4278470305930, 18062827159136, 76263743441314, 322033566728056 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 3..1000

FORMULA

G.f.: x^3*C(x)^8/(1 - x/sqrt(1-4*x)). - G. C. Greubel, Jul 19 2019

a(n) ~ phi^(3*n-4) / sqrt(5), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Jul 19 2019

MATHEMATICA

Drop[CoefficientList[Series[(1-Sqrt[1-4x])^8/(2^8*x^5*(1-x/Sqrt[1-4x])), {x, 0, 40}], x], 3] (* G. C. Greubel, Jul 19 2019 *)

PROG

(PARI) my(x='x+O('x^40)); Vec((1-sqrt(1-4*x))^8/(2^8*x^5*(1-x/sqrt(1-4*x)))) \\ G. C. Greubel, Jul 19 2019

(MAGMA) R<x>:=PowerSeriesRing(Rationals(), 40); Coefficients(R!( (1-Sqrt(1-4*x))^8/(2^8*x^5*(1-x/Sqrt(1-4*x))) )); // G. C. Greubel, Jul 19 2019

(Sage) a=((1-sqrt(1-4*x))^8/(2^8*x^5*(1-x/sqrt(1-4*x)))).series(x, 45).coefficients(x, sparse=False); a[3:40] # G. C. Greubel, Jul 19 2019

CROSSREFS

Cf. A000108, A026736.

Sequence in context: A005770 A030053 A072844 * A244650 A097790 A183805

Adjacent sequences:  A026854 A026855 A026856 * A026858 A026859 A026860

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified September 22 12:34 EDT 2020. Contains 337289 sequences. (Running on oeis4.)