A026759 a(n) = T(2n, n), T given by A026758.

1, 2, 7, 27, 109, 453, 1922, 8284, 36155, 159435, 709246, 3178992, 14343567, 65099245, 297015765, 1361584755, 6268757195, 28975155915, 134410918700, 625578384150, 2920488902795, 13672762887465, 64179220019365, 301987822527627

Offset

0,2

Links

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

Formula

a(n) = A002212(n+1) - A000245(n). - David Callan, Feb 01 2014

G.f.: ((1-x)*sqrt(1 - 4*x) - sqrt(1 - 6*x + 5*x^2))/(2*x^2). - G. C. Greubel, Oct 31 2019

Maple

seq(coeff(series(((1-x)*sqrt(1-4*x) - sqrt(1 -6*x +5*x^2))/(2*x^2), x, n+2), x, n), n = 0..30); # G. C. Greubel, Oct 31 2019

Mathematica

CoefficientList[Normal[Series[((1-x)Sqrt[1-4x] -Sqrt[1-6x+5x^2])/(2x^2), {x, 0, 30}]], x] (* David Callan, Feb 01 2014 *)

Prog

(PARI) my(x='x+O('x^30)); Vec(((1-x)*sqrt(1 - 4*x) - sqrt(1 - 6*x + 5*x^2))/(2*x^2)) \\ G. C. Greubel, Oct 31 2019
(Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( ((1-x)*Sqrt(1 - 4*x) - Sqrt(1 - 6*x + 5*x^2))/(2*x^2) )); // G. C. Greubel, Oct 31 2019
(Sage)
def A077952_list(prec):
    P.<x> = PowerSeriesRing(ZZ, prec)
    return P(((1-x)*sqrt(1-4*x) - sqrt(1-6*x+5*x^2))/(2*x^2)).list()
A077952_list(30) # G. C. Greubel, Oct 31 2019

Crossrefs

Cf. A026758, A026760, A026761, A026762, A026763, A026764, A026765, A026766, A026767, A026768.

Sequence in context: A026726 A150597 A150598 * A361778 A150599 A150600

Adjacent sequences: A026756 A026757 A026758 * A026760 A026761 A026762

Keyword

nonn

Author

Clark Kimberling

Status

approved