A131731 Period 4: repeat [2, -3, 4, -3].

2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3, 2, -3, 4, -3

Offset

0,1

Links

Table of n, a(n) for n=0..91.

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

Formula

From Luce ETIENNE, Mar 25 2017: (Start)

a(n)= (6*(-1)^n-(-1)^((2*n+1-(-1)^n)/4)-(-1)^((2*n-1+(-1)^n)/4))/2.

a(n) = 3*cos(n*Pi)-cos(n*Pi/2). (End)

Crossrefs

Sequence in context: A214551 A343435 A211010 * A255480 A356014 A309859

Adjacent sequences: A131728 A131729 A131730 * A131732 A131733 A131734

Keyword

sign,easy

Author

Paul Curtz, Sep 17 2007

Extensions

Better name from Joerg Arndt, Apr 02 2017

Status

approved