A131464 a(n) = 4*n^3 - 3*n^2 + 2*n - 1.

2, 23, 86, 215, 434, 767, 1238, 1871, 2690, 3719, 4982, 6503, 8306, 10415, 12854, 15647, 18818, 22391, 26390, 30839, 35762, 41183, 47126, 53615, 60674, 68327, 76598, 85511, 95090, 105359, 116342, 128063, 140546, 153815, 167894, 182807, 198578, 215231, 232790

Offset

1,1

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

G.f.: x*(2 + 15*x + 6*x^2 + x^3)/(1 - x)^4. - Vincenzo Librandi, Feb 12 2013

a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). - Vincenzo Librandi, Feb 12 2013

Mathematica

CoefficientList[Series[(2 + 15 x + 6 x^2 + x^3)/(1 - x)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Feb 12 2013 *)
Table[4n^3-3n^2+2n-1, {n, 40}] (* or *) LinearRecurrence[{4, -6, 4, -1}, {2, 23, 86, 215}, 40] (* Harvey P. Dale, May 05 2018 *)

Prog

(Magma) [4*n^3-3*n^2+2*n-1: n in [1..40]]; /* or */ I:=[2, 23, 86, 215]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Feb 12 2013

Crossrefs

Cf. A084849, A056109, A056105, A056578.

Sequence in context: A222564 A099134 A069152 * A245331 A270868 A239186

Adjacent sequences: A131461 A131462 A131463 * A131465 A131466 A131467

Keyword

nonn,easy

Author

Mohammad K. Azarian, Jul 26 2007

Status

approved