A166523 a(n) = 8*n - a(n-1), with n>1, a(1)=1.

1, 15, 9, 23, 17, 31, 25, 39, 33, 47, 41, 55, 49, 63, 57, 71, 65, 79, 73, 87, 81, 95, 89, 103, 97, 111, 105, 119, 113, 127, 121, 135, 129, 143, 137, 151, 145, 159, 153, 167, 161, 175, 169, 183, 177, 191, 185, 199, 193, 207, 201, 215, 209, 223, 217, 231, 225, 239, 233

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

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

Formula

G.f. -x*(-1-14*x+7*x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Mar 08 2011

From G. C. Greubel, May 16 2016: (Start)

E.g.f.: 5*exp(-x) + 2*(1 + 2*x)*exp(x) - 7.

a(n) = a(n-1) + a(n-2) - a(n-3). (End)

Sum_{n>=1} (-1)^(n+1)/a(n) = 1/7 + (1/8 + 1/(4*sqrt(2)))*Pi. - Amiram Eldar, Feb 24 2023

Mathematica

CoefficientList[Series[-(-1 - 14 x + 7 x^2)/((1 + x) (x - 1)^2), {x, 0, 60}], x] (* Vincenzo Librandi, Sep 13 2013 *)

Prog

(Magma) [n eq 1 select 1 else 8*n-Self(n-1): n in [1..70]]; // Vincenzo Librandi, Sep 13 2013

Crossrefs

Sequence in context: A182165 A139725 A009929 * A123542 A215236 A040212

Adjacent sequences: A166520 A166521 A166522 * A166524 A166525 A166526

Keyword

nonn,easy

Author

Vincenzo Librandi, Oct 16 2009

Status

approved