A168337 a(n) = 1 + 7*floor(n/2).

1, 8, 8, 15, 15, 22, 22, 29, 29, 36, 36, 43, 43, 50, 50, 57, 57, 64, 64, 71, 71, 78, 78, 85, 85, 92, 92, 99, 99, 106, 106, 113, 113, 120, 120, 127, 127, 134, 134, 141, 141, 148, 148, 155, 155, 162, 162, 169, 169, 176, 176, 183, 183, 190, 190, 197, 197, 204, 204, 211

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

a(n) = 7*n - a(n-1) - 5, with n>1, a(1)=1.

From Vincenzo Librandi, Sep 18 2013: (Start)

G.f.: x*(1 + 7*x - x^2)/((1+x)*(x-1)^2).

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

a(n) = (14*n + 7*(-1)^n - 3)/4. (End)

a(n) = A168333(n) - 1 = A168374(n) + 1. - Bruno Berselli, Sep 18 2013

E.g.f.: (1/2)*(-2 + (7*x + 2)*cosh(x) + (7*x - 5)*sinh(x)). - G. C. Greubel, Jul 18 2016

Mathematica

Table[ 1 + 7*floor(n/2) , {n, 60}] (* Bruno Berselli, Sep 18 2013 *)
CoefficientList[Series[(1 + 7 x - x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 18 2013 *)

Prog

(Magma) [7*n/2 + 7*(-1)^n/4 - 3/4: n in [1..70]]; // Vincenzo Librandi, Sep 18 2013

Crossrefs

Cf. A016993, A168333, A168374.

Sequence in context: A363326 A343526 A335896 * A109540 A229554 A298182

Adjacent sequences: A168334 A168335 A168336 * A168338 A168339 A168340

Keyword

nonn,easy,less

Author

Vincenzo Librandi, Nov 23 2009

Extensions

New definition by Bruno Berselli, Sep 18 2013

Status

approved