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A033580 Four times second pentagonal numbers: a(n) = 2*n*(3*n+1). 12
0, 8, 28, 60, 104, 160, 228, 308, 400, 504, 620, 748, 888, 1040, 1204, 1380, 1568, 1768, 1980, 2204, 2440, 2688, 2948, 3220, 3504, 3800, 4108, 4428, 4760, 5104, 5460, 5828, 6208, 6600, 7004, 7420, 7848 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Subsequence of A062717: A010052(6*a(n)+1) = 1. - Reinhard Zumkeller, Feb 21 2011

Sequence found by reading the line from 0, in the direction 0, 8,..., in the square spiral whose vertices are the generalized pentagonal numbers A001318. Opposite numbers to the members of A139267 in the same spiral - Omar E. Pol, Sep 09 2011

LINKS

Ivan Panchenko, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

a(n) = 12*n+a(n-1)-4 (with a(0)=0). - Vincenzo Librandi, Aug 05 2010

G.f.: 4*x*(2+x)/(1-x)^3. - Colin Barker, Feb 13 2012

a(-n) = A033579(n). - Michael Somos, Jun 09 2014

MATHEMATICA

s=0; lst={s}; Do[s+=n++ +8; AppendTo[lst, s], {n, 0, 8!, 12}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 16 2008 *)

PROG

(PARI) a(n)=2*n*(3*n+1) \\ Charles R Greathouse IV, Sep 28 2015

CROSSREFS

Cf. A049451, A045945, A033579, A186423.

Cf. sequences listed in A254963.

Sequence in context: A173681 A045850 A264354 * A212515 A007331 A002408

Adjacent sequences:  A033577 A033578 A033579 * A033581 A033582 A033583

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified December 12 15:01 EST 2017. Contains 295939 sequences.