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A173307 a(n) = 13*n*(n+1). 2
0, 26, 78, 156, 260, 390, 546, 728, 936, 1170, 1430, 1716, 2028, 2366, 2730, 3120, 3536, 3978, 4446, 4940, 5460, 6006, 6578, 7176, 7800, 8450, 9126, 9828, 10556, 11310, 12090, 12896, 13728, 14586, 15470, 16380, 17316, 18278, 19266, 20280 (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 (3,-3,1).

FORMULA

a(n) = 26 * A000217(n).

G.f.: 26*x/(1-x)^3. - Vincenzo Librandi, Sep 28 2013

a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Vincenzo Librandi, Sep 28 2013

MATHEMATICA

Table[13 n (n + 1), {n, 0, 50}] (* or *) CoefficientList[Series[26 x/(1 - x)^3, {x, 0, 50}], x] (* Vincenzo Librandi, Sep 28 2013 *)

LinearRecurrence[{3, -3, 1}, {0, 26, 78}, 50] (* Harvey P. Dale, Apr 08 2014 *)

PROG

(MAGMA) [13*n*(n+1): n in [0..40]]; /* or */ I:=[0, 26, 78]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+Self(n-3): n in [1..40]]; // Vincenzo Librandi, Sep 28 2013

(PARI) a(n)=13*n*(n+1) \\ Charles R Greathouse IV, Jun 17 2017

CROSSREFS

Cf. A262221.

Sequence in context: A124719 A126380 A083578 * A042326 A042328 A042330

Adjacent sequences:  A173304 A173305 A173306 * A173308 A173309 A173310

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 16 2010

EXTENSIONS

Incorrect formulas and examples deleted by R. J. Mathar, Jan 04 2011

STATUS

approved

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Last modified November 21 01:23 EST 2019. Contains 329348 sequences. (Running on oeis4.)