

A153784


4 times heptagonal numbers: 2n(5n3).


3



0, 4, 28, 72, 136, 220, 324, 448, 592, 756, 940, 1144, 1368, 1612, 1876, 2160, 2464, 2788, 3132, 3496, 3880, 4284, 4708, 5152, 5616, 6100, 6604, 7128, 7672, 8236, 8820, 9424, 10048, 10692, 11356, 12040, 12744, 13468, 14212, 14976, 15760
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,2


COMMENTS

Sequence found by reading the line from 0, in the direction 0, 4,..., in the square spiral whose vertices are the generalized heptagonal numbers A085787.  Omar E. Pol, Jul 18 2012


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) = 10n^2  6n = A000566(n)*4 = A135706(n)*2.
a(n)=20*n+a(n1)16 (with a(0)=0)  Vincenzo Librandi, Aug 03 2010
a(n) = A087348(n)  1, n >= 1.  Omar E. Pol, Jul 18 2012
a(0)=0, a(1)=4, a(2)=28, a(n)=3*a(n1)3*a(n2)+a(n3).  Harvey P. Dale, Mar 19 2015


MATHEMATICA

s=0; lst={s}; Do[s+=n; AppendTo[lst, s], {n, 4, 6!, 20}]; lst (* Vladimir Joseph Stephan Orlovsky, Apr 02 2009 *)
Table[2n(5n3), {n, 0, 40}] (* or *) LinearRecurrence[{3, 3, 1}, {0, 4, 28}, 50] (* Harvey P. Dale, Mar 19 2015 *)


PROG

(PARI) a(n)=2*n*(5*n3) \\ Charles R Greathouse IV, Jun 17 2017


CROSSREFS

Cf. A000566, A135706, A152773, A152785.
Sequence in context: A203280 A085024 A085001 * A030117 A005634 A183485
Adjacent sequences: A153781 A153782 A153783 * A153785 A153786 A153787


KEYWORD

easy,nonn


AUTHOR

Omar E. Pol, Jan 02 2009


STATUS

approved



