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A131185 Period 6: repeat [0, 2, -1, 0, -1, 3]. 1
0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3, 0, 2, -1, 0, -1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..89.

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

FORMULA

a(n) = (1/30)*{16*(n mod 6)-19*[(n+1) mod 6]+6*[(n+2) mod 6]-4*[(n+3) mod 6]+16*[(n+4) mod 6]-9*[(n+5) mod 6]}. - Paolo P. Lava, Oct 24 2007

a(n) = a(n-6) for n>5. G.f.: x*(2-x-x^3+3*x^4)/((1-x)*(1+x)*(1+x+x^2)*(1-x+x^2)). - R. J. Mathar, Feb 07 2009

a(n) = sin(n*Pi/3)*(6*sin(n*Pi/3) + 14*sin(2*n*Pi/3) - 2*sqrt(3)*cos(n*Pi/3) - sqrt(3))/6. - Wesley Ivan Hurt, Jun 19 2016

MAPLE

A131185:=n->[0, 2, -1, 0, -1, 3][(n mod 6)+1]: seq(A131185(n), n=0..100); # Wesley Ivan Hurt, Jun 19 2016

MATHEMATICA

PadRight[{}, 120, {0, 2, -1, 0, -1, 3}] (* Harvey P. Dale, Dec 29 2012 *)

PROG

(MAGMA) &cat[[0, 2, -1, 0, -1, 3]^^20]; // Wesley Ivan Hurt, Jun 19 2016

(PARI) a(n)=[0, 2, -1, 0, -1, 3][n%6+1] \\ Charles R Greathouse IV, Jul 26 2016

CROSSREFS

Sequence in context: A231119 A129558 A267181 * A307819 A286354 A296067

Adjacent sequences:  A131182 A131183 A131184 * A131186 A131187 A131188

KEYWORD

sign,easy

AUTHOR

Paul Curtz, Sep 25 2007

EXTENSIONS

More periods from R. J. Mathar, Feb 07 2009

STATUS

approved

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Last modified June 18 14:54 EDT 2021. Contains 345119 sequences. (Running on oeis4.)