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A131869 Expansion of series reversion of x*(1-8*x)/(1-x). 4
1, 7, 105, 1967, 41265, 927479, 21838425, 531731935, 13278739425, 338235642983, 8753720757705, 229531493157519, 6084679071674385, 162802128960940119, 4390789738688043705, 119242319290800424383, 3258012200816503807425, 89495966923044854350535, 2470171286283446551216425 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The Hankel transform of this sequence is 56^C(n+1,2) .

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..675

FORMULA

a(n) = Sum_{k=0..n} A086810(n,k)*7^k.

From Vaclav Kotesovec, Aug 20 2013: (Start)

G.f.: (x-15-sqrt(x^2-30*x+1))/16.

Recurrence: n*a(n) = 15*(2*n-3)*a(n-1) - (n-3)*a(n-2).

a(n) ~ sqrt(30*sqrt(14)-112)*(15+4*sqrt(14))^n/(16*sqrt(Pi)*n^(3/2)). (End)

G.f.: x/(1 - 7*x/(1 - 8*x/(1 - 7*x/(1 - 8*x/(1 - 7*x/(1 - ...)))))), a continued fraction. - Ilya Gutkovskiy, Apr 20 2017

MATHEMATICA

Rest[CoefficientList[InverseSeries[Series[x*(1-8*x)/(1-x), {x, 0, 20}], x], x]] (* Vaclav Kotesovec, Aug 20 2013 *)

PROG

(PARI) Vec(serreverse(x*(1-8*x)/(1-x)+O(x^66))) /* Joerg Arndt, Feb 06 2013 */

CROSSREFS

Sequence in context: A139742 A120049 A067420 * A132867 A145666 A238464

Adjacent sequences:  A131866 A131867 A131868 * A131870 A131871 A131872

KEYWORD

nonn

AUTHOR

Philippe Deléham, Oct 29 2007

EXTENSIONS

More terms from Philippe Deléham, Feb 06 2013

Offset corrected, Joerg Arndt, Feb 15 2013

STATUS

approved

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Last modified September 16 08:36 EDT 2019. Contains 327091 sequences. (Running on oeis4.)