A101825 G.f.: x*(1+x)^2/(1-x^3).

0, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2

Offset: 0

Author

N. J. A. Sloane, Jun 17 2007

Keywords

• nonn
• easy

Comments

Period 3. Used in A042965.

First differences are essentially A049347. The binomial transform yields 0, 1, 4, 10,... i.e. A111927 with the first two zeros removed. - R. J. Mathar, May 14 2008

Links

• Index entries for linear recurrences with constant coefficients, signature (0,0,1).

Programs

Mathematica

LinearRecurrence[{0,0,1},{0,1,2,1},120] (* Harvey P. Dale, Aug 01 2016 *)

PARI

x='x+O('x^50); Vec(x*(1+x)^2/(1-x^3)) \\ G. C. Greubel, May 03 2017

Formula

a(n) = A100063(n+1), n>0. - R. J. Mathar, Sep 01 2008