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A033587
a(n) = 2*n*(4*n + 3).
11
0, 14, 44, 90, 152, 230, 324, 434, 560, 702, 860, 1034, 1224, 1430, 1652, 1890, 2144, 2414, 2700, 3002, 3320, 3654, 4004, 4370, 4752, 5150, 5564, 5994, 6440, 6902, 7380, 7874, 8384, 8910, 9452, 10010, 10584, 11174, 11780, 12402, 13040, 13694, 14364, 15050
OFFSET
0,2
COMMENTS
The inverse binomial transform is [0, 14, 16, 0, 0, 0, ...]. - R. J. Mathar, May 06 2008
Sequence found by reading the line from 0, in the direction 0, 14, ..., in the square spiral whose vertices are the triangular numbers A000217. Opposite numbers to the even hexagonal numbers A014635 in the same spiral. - Omar E. Pol, Sep 03 2011
FORMULA
a(n) = 2*A033954(n).
O.g.f.: 2*x*(7+x)/(1-x)^3. - R. J. Mathar, May 06 2008
a(n) = 16*n + a(n-1) - 2 with a(0)=0. - Vincenzo Librandi, Aug 05 2010
E.g.f.: (8*x^2 + 14*x)*exp(x). - G. C. Greubel, Jul 18 2017
From Vaclav Kotesovec, Aug 18 2018: (Start)
Sum_{n>=1} 1/a(n) = 2/9 + Pi/12 - log(2)/2.
Sum_{n>=1} (-1)^n/a(n) = 2/9 - Pi/(6*sqrt(2)) - log(2)/6 + log(1+sqrt(2))/(3*sqrt(2)). (End)
MATHEMATICA
Table[2*n(4*n + 3), {n, 0, 100}] (* Vladimir Joseph Stephan Orlovsky, Jun 26 2011 *)
LinearRecurrence[{3, -3, 1}, {0, 14, 44}, 80] (* Harvey P. Dale, Jun 05 2019 *)
PROG
(PARI) a(n)=2*n*(4*n+3) \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Sequence in context: A064125 A089031 A265152 * A189807 A009942 A031130
KEYWORD
nonn,easy
STATUS
approved