A146885 a(n) = 8*Sum_{k=0..n} 7^k.

8, 64, 456, 3200, 22408, 156864, 1098056, 7686400, 53804808, 376633664, 2636435656, 18455049600, 129185347208, 904297430464, 6330082013256, 44310574092800, 310174018649608, 2171218130547264, 15198526913830856

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8,-7).

Formula

From G. C. Greubel, Oct 12 2022: (Start)

a(n) = (4/3)*(7^(n+1) - 1).

a(n) = 8*A023000(n+1).

a(n) = 8*a(n-1) - 7*a(n-2).

G.f.: 8/((1-x)*(1-7*x)).

E.g.f.: (4/3)*(7*exp(7*x) - exp(x)). (End)

Mathematica

a[n_]:= Sum[8*7^m, {m, 0, n}]; Table[a[n], {n, 0, 30}]
LinearRecurrence[{8, -7}, {8, 64}, 41] (* G. C. Greubel, Oct 12 2022 *)

Prog

(Magma) [n le 2 select 8^n else 8*Self(n-1) -7*Self(n-2): n in [1..41]]; // G. C. Greubel, Oct 12 2022
(SageMath) [(4/3)*(7^(n+1)-1) for n in range(41)] # G. C. Greubel, Oct 12 2022

Crossrefs

Cf. A005843, A023000, A068156, A100774, A132583, A146882, A146883, A146885.

Sequence in context: A239034 A213296 A223564 * A122093 A267231 A267470

Adjacent sequences: A146882 A146883 A146884 * A146886 A146887 A146888

Keyword

nonn,easy,less

Author

Roger L. Bagula, Nov 02 2008

Status

approved