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A131554 Period 5: repeat [1, 1, -1, 1, -1]. 0
1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..69.

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

FORMULA

a(n) = (1/50)*{-19*(n mod 5)+21*[(n+1) mod 5]-19*[(n+2) mod 5]+21*[(n+3) mod 5]+[(n+4) mod 5]}, with n>=0. - Paolo P. Lava, Aug 28 2007

G.f.: (-1-x+x^2-x^3+x^4)/(x-1)/(1+x+x^2+x^3+x^4). - R. J. Mathar, Nov 14 2007

a(0)=1, a(1)=1, a(2)=-1, a(3)=1, a(4)=-1, a(n)=a(n-5). - Harvey P. Dale, Jul 05 2013

a(n) = (1 - 4*(cos(4*(n-4)*Pi/5) + cos(2*(n-2)*Pi/5) + cos(4*(n-2)*Pi/5) + cos(2*(n+1)*Pi/5)))/5. - Wesley Ivan Hurt, Sep 27 2018

MATHEMATICA

PadRight[{}, 120, {1, 1, -1, 1, -1}] (* or *) LinearRecurrence[{0, 0, 0, 0, 1}, {1, 1, -1, 1, -1}, 120] (* Harvey P. Dale, Jul 05 2013 *)

PROG

(PARI) Vec((1+x-x^2+x^3-x^4)/(1-x)/(1+x+x^2+x^3+x^4)+O(x^99)) \\ Charles R Greathouse IV, Jun 13 2013

CROSSREFS

Sequence in context: A321753 A186032 A212157 * A153881 A160357 A186039

Adjacent sequences:  A131551 A131552 A131553 * A131555 A131556 A131557

KEYWORD

sign,easy,less

AUTHOR

Paul Curtz, Aug 26 2007

STATUS

approved

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Last modified February 25 21:32 EST 2020. Contains 332258 sequences. (Running on oeis4.)