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A152965
Twice 12-gonal numbers: a(n) = 2*n*(5*n-4).
5
0, 2, 24, 66, 128, 210, 312, 434, 576, 738, 920, 1122, 1344, 1586, 1848, 2130, 2432, 2754, 3096, 3458, 3840, 4242, 4664, 5106, 5568, 6050, 6552, 7074, 7616, 8178, 8760, 9362, 9984, 10626, 11288, 11970, 12672, 13394, 14136, 14898, 15680, 16482, 17304, 18146, 19008
OFFSET
0,2
FORMULA
a(n) = 2*A051624(n).
From Vincenzo Librandi, Jul 10 2012: (Start)
G.f.: 2*x*(1+9*x)/(1-x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). (End)
From Elmo R. Oliveira, Dec 27 2024: (Start)
E.g.f.: 2*exp(x)*x*(1 + 5*x).
a(n) = n + A051874(n). (End)
MATHEMATICA
Table[10*n^2-8*n, {n, 0, 50}] (* Vincenzo Librandi, Jul 10 2012 *)
LinearRecurrence[{3, -3, 1}, {0, 2, 24}, 60] (* Harvey P. Dale, Apr 18 2016 *)
PROG
(Magma) [10*n^2-8*n: n in [0..50]]; // Klaus Brockhaus, Nov 27 2010
(PARI) a(n)=2*n*(5*n-4) \\ Charles R Greathouse IV, Oct 07 2015
CROSSREFS
Cf. A051624 (12-gonal numbers), A051874.
Cf. numbers of the form n*(n*k - k + 4)/2 listed in A226488 (this sequence is the case k=20). - Bruno Berselli, Jun 10 2013
Sequence in context: A292162 A068878 A100918 * A345692 A139284 A003614
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Dec 21 2008
STATUS
approved