A128793 n^3*7^n.

0, 7, 392, 9261, 153664, 2100875, 25412184, 282475249, 2951578112, 29417779503, 282475249000, 2631821894933, 23917744283328, 212865155864179, 1861044111897656, 16023020096057625, 136122083613085696

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (28,-294,1372,-2401).

Formula

G.f.: 7*x*(1 + 28*x + 49x^2)/(1 - 7*x)^4. - Vincenzo Librandi, Feb 08 2013

a(n) = 28*a(n-1) - 294*a(n-2) + 1372*a(n-3) - 2401*a(n-4). - Vincenzo Librandi, Feb 09 2013

Mathematica

CoefficientList[Series[7*x*(1 + 28*x + 49*x^2)/(1 - 7*x)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Feb 08 2013 *)
Table[n^3 7^n, {n, 0, 20}] (* or *) LinearRecurrence[{28, -294, 1372, -2401}, {0, 7, 392, 9261}, 20] (* Harvey P. Dale, Aug 30 2020 *)

Prog

(Magma) [n^3*7^n: n in [0..20]]; // Vincenzo Librandi, Feb 08 2013
(Magma) I:=[0, 7, 392, 9261]; [n le 4 select I[n] else 28*Self(n-1)-294*Self(n-2)+1372*Self(n-3)-2401*Self(n-4): n in [1..30]]; // Vincenzo Librandi, Feb 09 2013

Crossrefs

Cf. A036289, A007758.

Sequence in context: A185354 A222893 A009712 * A042527 A203588 A015022

Adjacent sequences: A128790 A128791 A128792 * A128794 A128795 A128796

Keyword

nonn,easy

Author

Mohammad K. Azarian, Apr 07 2007

Status

approved