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URL: https://oeis.org/A270472

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A270472
Expansion of g.f. (1-2*x)/(1-9*x).
3
1, 7, 63, 567, 5103, 45927, 413343, 3720087, 33480783, 301327047, 2711943423, 24407490807, 219667417263, 1977006755367, 17793060798303, 160137547184727, 1441237924662543, 12971141321962887, 116740271897665983, 1050662447078993847, 9455962023710944623, 85103658213398501607
OFFSET
0,2
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.
a(n) = A005032(2*n-2). - R. J. Mathar, Jan 28 2025
E.g.f.: (7*exp(9*x) + 2)/9. - Elmo R. Oliveira, Mar 25 2025
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), A005032, 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
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Mar 17 2016
STATUS
approved