A162256 a(n) = (2*n^3 + 5*n^2 - 3*n)/2.

2, 15, 45, 98, 180, 297, 455, 660, 918, 1235, 1617, 2070, 2600, 3213, 3915, 4712, 5610, 6615, 7733, 8970, 10332, 11825, 13455, 15228, 17150, 19227, 21465, 23870, 26448, 29205, 32147, 35280, 38610, 42143, 45885, 49842, 54020, 58425, 63063, 67940

Offset: 1

Author

Vincenzo Librandi, Jun 29 2009

Keywords

• nonn
• easy

Comments

Row sums from A154680.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Programs

Mathematica

LinearRecurrence[{4,-6,4,-1}, {2, 15, 45, 98}, 50] (* or *) CoefficientList[Series[(2+7*x-3*x^2)/(1-x)^4,{x,0,39}],x] (* Vincenzo Librandi, Mar 04 2012 *)

PARI

n*(5*n-3)/2+n^3 \\ Charles R Greathouse IV, Jan 11 2012

Formula

From Vincenzo Librandi, Mar 04 2012: (Start)

G.f.: x*(2 + 7*x - 3*x^2)/(1-x)^4.

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)