A146882 a(n) = 5*(4^(n+1) - 1)/3.

5, 25, 105, 425, 1705, 6825, 27305, 109225, 436905, 1747625, 6990505, 27962025, 111848105, 447392425, 1789569705, 7158278825, 28633115305, 114532461225, 458129844905, 1832519379625, 7330077518505, 29320310074025

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (5,-4).

Formula

a(n) = 5*A002450(n+1).

G.f.: 5 / ( (1-x)*(1-4*x) ). - R. J. Mathar, Jun 26 2011

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

a(n) = (5/3)*A000051(n+1)*A000225(n+1).

E.g.f.: (5/3)*(4*exp(4*x) - exp(x)). (End)

Mathematica

Table[5*(4^(n+1) -1)/3, {n, 0, 40}]

Prog

(Magma) [5*(4^(n+1)-1)/3: n in [0..40]]; // Vincenzo Librandi, Jul 15 2011
(PARI) a(n)=20<<(2*n)\/3-2 \\ Charles R Greathouse IV, Jul 15 2011
(SageMath) [(5/3)*(2^(2*n+2)-1) for n in range(41)] # G. C. Greubel, Oct 12 2022

Crossrefs

Cf. A000051, A000225, A002450, A100774.

Sequence in context: A209836 A272762 A245551 * A218264 A264018 A067971

Adjacent sequences: A146879 A146880 A146881 * A146883 A146884 A146885

Keyword

nonn,easy

Author

Roger L. Bagula, Nov 02 2008

Status

approved