A128989 a(n) = (n^3 - n^2)*6^n.

0, 144, 3888, 62208, 777600, 8398080, 82301184, 752467968, 6530347008, 54419558400, 438984437760, 3448023220224, 26487087464448, 199671890116608, 1481082701414400, 10833062044631040, 78268873272459264

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (24,-216,864,-1296).

Formula

G.f.: 144*x^2*(1+3*x)/(1-6*x)^4. - Vincenzo Librandi, Feb 12 2013

a(n) = 24*a(n-1)-216*a(n-2)+864*a(n-3)-1296*a(n-4). - Vincenzo Librandi, Feb 12 2013

Mathematica

CoefficientList[Series[144 x (1 + 3 x)/(1 - 6 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 12 2013 *)
Table[(n^3-n^2)6^n, {n, 20}] (* or *) LinearRecurrence[{24, -216, 864, -1296}, {0, 144, 3888, 62208}, 20] (* Harvey P. Dale, Apr 29 2019 *)

Prog

(Magma) [(n^3-n^2)*6^n: n in [1..25]]; /* or */ I:=[0, 144, 3888, 62208]; [n le 4 select I[n] else 24*Self(n-1)-216*Self(n-2)+864*Self(n-3)-1296*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Feb 12 2013

Crossrefs

Cf. A128796, A036289.

Sequence in context: A253134 A168371 A339056 * A257298 A271672 A204390

Adjacent sequences: A128986 A128987 A128988 * A128990 A128991 A128992

Keyword

nonn,easy

Author

Mohammad K. Azarian, Apr 30 2007

Extensions

Offset corrected by Mohammad K. Azarian, Nov 20 2008

Status

approved