A121607 (n^3+n)*3^n.

6, 90, 810, 5508, 31590, 161838, 765450, 3411720, 14526054, 59639490, 237731274, 924707340, 3523453830, 13191428502, 48642794730, 177008116752, 636661003590, 2266409860650, 7994034370026, 27964010896020, 97092998430246

Offset: 1

Author

Mohammad K. Azarian, May 02 2007

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A128796, A128960, A128985, A129002.

Programs

Magma

[(n^3 + n)*3^n: n in [1..30]]; // Vincenzo Librandi, Feb 22 2013

Mathematica

Table[(n^3 + n)*3^n, {n, 30}] (* or *) CoefficientList[Series[6 (1 + 3 x + 9 x^2)/(1 - 3 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 22 2013 *)

Formula

G.f.: 6*x*(1 + 3*x + 9*x^2)/(1 - 3*x)^4. - Vincenzo Librandi, Feb 22 2013