A121204 -2n+7^n-5^n.

0, 0, 20, 212, 1768, 13672, 102012, 745404, 5374160, 38400464, 272709604, 1928498596, 13597146552, 95668307256, 672119557196, 4717043931788, 33080342678944, 231867574534048, 1624598900644788, 11379821699044980

Offset: 0

Author

Mohammad K. Azarian, Aug 19 2006

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (14,-60,82,-35).

Crossrefs

Cf. A074616.

Programs

Magma

I:=[0, 0, 20, 212]; [n le 4 select I[n] else 14*Self(n-1)-60*Self(n-2)+82*Self(n-3)-35*Self(n-4): n in [1..20]]; // Vincenzo Librandi, Feb 26 2013

Mathematica

CoefficientList[Series[4 x^2 (5 - 17 x)/((1 - x)^2 (1 - 5 x)(1 - 7 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 26 2013 *)
LinearRecurrence[{14,-60,82,-35},{0,0,20,212},20] (* Harvey P. Dale, Nov 30 2022 *)

Formula

G.f.: 4*x^2*(5-17*x)/((1-x)^2 (1-5*x)(1-7*x)). - Vincenzo Librandi. Feb 26 2013

a(n) = 14*a(n-1)-60*a(n-2)+82*a(n-3)-35*a(n-4). - Vincenzo Librandi, Feb 26 2013

Extensions

Edited by Ray Chandler, Sep 06 2006