A130566 Pyramidal 47-gonal numbers.

1, 48, 186, 460, 915, 1596, 2548, 3816, 5445, 7480, 9966, 12948, 16471, 20580, 25320, 30736, 36873, 43776, 51490, 60060, 69531, 79948, 91356, 103800, 117325, 131976, 147798, 164836, 183135, 202740, 223696, 246048, 269841, 295120, 321930, 350316, 380323

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Formula

(15 n + 1) (n + 2) (n + 1)/2.

G.f.: (1+44*x)/(1-x)^4. [Colin Barker, Apr 30 2012]

a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4). - Vincenzo Librandi, Jun 29 2012

Mathematica

CoefficientList[Series[(1+44*x)/(1-x)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 29 2012 *)

Prog

(Magma) I:=[1, 48, 186, 460]; [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, Jun 29 2012

Crossrefs

Sequence in context: A233682 A233675 A005911 * A233792 A233967 A233785

Adjacent sequences: A130563 A130564 A130565 * A130567 A130568 A130569

Keyword

nonn,easy

Author

N. J. A. Sloane, Oct 06 2007, based on a suggestion from an unknown correspondent in 2004.

Status

approved