A162258 a(n) = (2*n^3 + 5*n^2 - 9*n)/2.

-1, 9, 36, 86, 165, 279, 434, 636, 891, 1205, 1584, 2034, 2561, 3171, 3870, 4664, 5559, 6561, 7676, 8910, 10269, 11759, 13386, 15156, 17075, 19149, 21384, 23786, 26361, 29115, 32054, 35184, 38511, 42041, 45780, 49734, 53909, 58311, 62946, 67820

Offset

1,2

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).

Formula

Row sums from A155546: a(n) = Sum_{m=1..n} (2*m*n + m + n - 5).

From Vincenzo Librandi, Mar 04 2012: (Start)

G.f.: x*(-1 + 13*x - 6*x^2)/(1-x)^4.

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

Mathematica

LinearRecurrence[{4, -6, 4, -1}, {-1, 9, 36, 86}, 50] (* or *) CoefficientList[Series[(2+7*x-3*x^2)/(1-x)^4, {x, 0, 50}], x] (* Vincenzo Librandi, Mar 04 2012 *)

Crossrefs

Cf. A155546.

Sequence in context: A009522 A045851 A173243 * A128642 A342252 A226253

Adjacent sequences: A162255 A162256 A162257 * A162259 A162260 A162261

Keyword

sign,easy

Author

Vincenzo Librandi, Jun 29 2009

Extensions

New name from Vincenzo Librandi, Mar 04 2012

Status

approved