A270472 Expansion of (1-2*x)/(1-9*x).

1, 7, 63, 567, 5103, 45927, 413343, 3720087, 33480783, 301327047, 2711943423, 24407490807, 219667417263, 1977006755367, 17793060798303, 160137547184727, 1441237924662543, 12971141321962887, 116740271897665983, 1050662447078993847, 9455962023710944623

Offset

0,2

Links

Colin Barker, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (9).

Formula

G.f.: (1-2*x)/(1-9*x).

a(n) = 9*a(n-1) for n>1.

a(n) = 7*9^(n-1) for n>0.

Mathematica

CoefficientList[Series[(1 - 2 x)/(1 - 9 x), {x, 0, 20}], x] (* Michael De Vlieger, Mar 18 2016 *)

Prog

(PARI) Vec((1-2*x)/(1-9*x) + O(x^30))

Crossrefs

Cf. A001019 (powers of 9), A187709 (partial sums).

Cf. A055275: (1-x)/(1-9*x); A092810: (1-3*x)/(1-9*x).

Sequence in context: A024088 A291034 A155132 * A266426 A368164 A345078

Adjacent sequences: A270469 A270470 A270471 * A270473 A270474 A270475

Keyword

nonn,easy

Author

Colin Barker, Mar 17 2016

Status

approved