A130731 Period 4: repeat [1, 2, 0, 0].

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

Offset

0,2

Links

Table of n, a(n) for n=0..103.

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

Formula

a(n) = (n mod 4) mod 3, with offset 1..a(1)=1. - Gary Detlefs, Mar 28 2010

a(n) = floor(((2*n+4) mod 8)/3). - Gary Detlefs, Jul 02 2011

a(n) = (3-(-1)^n)*(1+I^((n-1)*n))/4. - Bruno Berselli, Sep 28 2011

G.f.: (1+2*x)/(1-x^4). - Bruno Berselli, Sep 28 2011

From Wesley Ivan Hurt, Jul 09 2016: (Start)

a(n) = (3 + 2*cos(n*Pi/2) - cos(n*Pi) + 4*sin(n*Pi/2) - I*sin(n*Pi))/4.

a(n) = a(n-4) for n>3. (End)

a(n) = n + 1 - floor((n+1)/4) - 3*floor((n+2)/4). - Ridouane Oudra, Apr 15 2021

Maple

seq(op([1, 2, 0, 0]), n=0..40); # Wesley Ivan Hurt, Jul 09 2016

Mathematica

PadRight[{}, 100, {1, 2, 0, 0}] (* Wesley Ivan Hurt, Jul 09 2016 *)
CoefficientList[Series[(1 + 2 x)/(1 - x^4), {x, 0, 80}], x] (* Michael De Vlieger, Dec 23 2016 *)

Prog

(Magma) &cat [[1, 2, 0, 0]^^30]; // Wesley Ivan Hurt, Jul 09 2016

Crossrefs

Sequence in context: A345957 A325189 A357637 * A287240 A025875 A026840

Adjacent sequences: A130728 A130729 A130730 * A130732 A130733 A130734

Keyword

nonn,easy

Author

Paul Curtz, Aug 17 2007

Extensions

Edited by N. J. A. Sloane, Sep 15 2007

Status

approved