A168437 a(n) = 3 + 10*floor(n/2).

3, 13, 13, 23, 23, 33, 33, 43, 43, 53, 53, 63, 63, 73, 73, 83, 83, 93, 93, 103, 103, 113, 113, 123, 123, 133, 133, 143, 143, 153, 153, 163, 163, 173, 173, 183, 183, 193, 193, 203, 203, 213, 213, 223, 223, 233, 233, 243, 243, 253, 253, 263, 263, 273, 273, 283

Offset

1,1

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) = 10*n - a(n-1) - 4, with n>1, a(1) = 3.

a(n) = 10*floor(n/2) + 3 = A168641(n) + 3. - Rick L. Shepherd, Jun 17 2010

G.f.: x*(3 + 10*x - 3*x^2)/((1+x)*(x-1)^2). - Vincenzo Librandi, Sep 19 2013

a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 19 2013

a(n) = (1 + 5*(-1)^n + 10*n)/2. - Bruno Berselli, Sep 19 2013

E.g.f.: (1/2)*(5 - 6*exp(x) + (10*x + 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 22 2016

Mathematica

Table[3 + 10 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[(3 + 10 x - 3 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
LinearRecurrence[{1, 1, -1}, {3, 13, 13}, 70] (* Harvey P. Dale, May 26 2021 *)

Prog

(PARI) a(n)=n\2*10+3 \\ Charles R Greathouse IV, Jan 11 2012
(Magma) [3+10*Floor(n/2): n in [1..70]]; // Vincenzo Librandi, Sep 19 2013

Crossrefs

Bisections of A168437 are A017305 and (A017305 MINUS {3}). - Rick L. Shepherd, Jun 17 2010

Sequence in context: A272825 A054767 A137947 * A076747 A198452 A286190

Adjacent sequences: A168434 A168435 A168436 * A168438 A168439 A168440

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 25 2009

Extensions

Edited by Rick L. Shepherd, Jun 17 2010

Definition rewritten, using Shepherd's formula, by Vincenzo Librandi, Sep 19 2013

Status

approved