A033573 a(n) = (2*n+1)*(9*n+1).

1, 30, 95, 196, 333, 506, 715, 960, 1241, 1558, 1911, 2300, 2725, 3186, 3683, 4216, 4785, 5390, 6031, 6708, 7421, 8170, 8955, 9776, 10633, 11526, 12455, 13420, 14421, 15458, 16531, 17640, 18785, 19966, 21183, 22436, 23725, 25050, 26411, 27808, 29241, 30710, 32215, 33756, 35333

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Formula

From G. C. Greubel, Oct 12 2019: (Start)

G.f.: (1 + 27*x + 8*x^2)/(1-x)^3.

E.g.f.: (1 + 29*x + 18*x^2)*exp(x). (End)

Sum 1/a(n) = -Psi(1/9)/7 -gamma/7 -2*log(2)/7 = 1.0634904644443440.. where gamma =A001620, Psi(1/9) = -A354636.

Maple

seq((2*n+1)*(9*n+1), n=0..50); # G. C. Greubel, Oct 12 2019

Mathematica

Table[(2*n+1)*(9*n+1), {n, 0, 50}] (* G. C. Greubel, Oct 12 2019 *)

Prog

(PARI) a(n)=(2*n+1)*(9*n+1) \\ Charles R Greathouse IV, Jun 17 2017
(Magma) [(2*n+1)*(9*n+1): n in [0..50]] # G. C. Greubel, Oct 12 2019
(Sage) [(2*n+1)*(9*n+1) for n in range(50)] # G. C. Greubel, Oct 12 2019
(GAP) List([0..50], n-> (2*n+1)*(9*n+1)); # G. C. Greubel, Oct 12 2019

Crossrefs

Sequence in context: A165133 A044217 A044598 * A035076 A308508 A096382

Adjacent sequences: A033570 A033571 A033572 * A033574 A033575 A033576

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved