A131756 Period 3: repeat [2, -1, 3].

2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3

Offset: 0

Author

Paul Curtz, Oct 04 2007

Keywords

• sign
• easy

Links

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

Crossrefs

Cf. A130784.

Programs

Magma

&cat [[2, -1, 3]^^30]; // Wesley Ivan Hurt, Jul 01 2016

Maple

seq(op([2, -1, 3]), n=0..50); # Wesley Ivan Hurt, Jul 01 2016

Mathematica

PadRight[{}, 100, {2, -1, 3}] (* Wesley Ivan Hurt, Jul 01 2016 *)

PARI

a(n)=[2,-1,3][1+n%3] \\ Jaume Oliver Lafont, Mar 24 2009

Formula

a(n) = 4/3+2/3*cos(2/3*Pi*n)-4/3*3^(1/2)*sin(2/3*Pi*n). - R. J. Mathar, Nov 15 2007

G.f.: (2-x+3*x^2)/(1-x^3). - Jaume Oliver Lafont, Mar 24 2009

a(n) = a(n-3) for n>2. - Wesley Ivan Hurt, Jul 01 2016