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A130566 Pyramidal 47-gonal numbers. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 6 11:55 EDT 2020. Contains 336246 sequences. (Running on oeis4.)