A128796 a(n) = n*(n-1)*2^n.

0, 0, 8, 48, 192, 640, 1920, 5376, 14336, 36864, 92160, 225280, 540672, 1277952, 2981888, 6881280, 15728640, 35651584, 80216064, 179306496, 398458880, 880803840, 1937768448, 4244635648, 9261023232, 20132659200, 43620761600, 94220845056, 202937204736, 435939180544

Offset: 0

Author

Mohammad K. Azarian, Apr 07 2007

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (6,-12,8).

Crossrefs

Cf. A001788, A007758, A036289.

Programs

Magma

[(n^2-n)*2^n: n in [0..30]]; // Vincenzo Librandi, Feb 10 2013

Mathematica

CoefficientList[Series[8 x^2/(1 - 2 x)^3, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 10 2013 *)

PARI

a(n)=n*(n-1)<Charles R Greathouse IV, Sep 24 2015

Formula

G.f.: 8*x^2/(1 - 2*x)^3. - Vincenzo Librandi, Feb 10 2013

a(n) = 8*A001788(n-1). - R. J. Mathar, Apr 26 2015

From Amiram Eldar, Jul 11 2020: (Start)

Sum_{n>=2} 1/a(n) = (1 - log(2))/2.

Sum_{n>=2} (-1)^n/a(n) = (3*log(3/2) - 1)/2. (End)

E.g.f.: 4*exp(2*x)*x^2. - Stefano Spezia, Sep 02 2024