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A216178 Period 4: repeat [4, 1, 0, -3]. 1
4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3, 4, 1, 0, -3 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..79.

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

FORMULA

a(n) = (3*(-1)^n+1)/2 + 2*(-1)^((2*n-1+(-1)^n)/4).

a(n) = A168361(n+1) + A084100(n+4).

G.f.: (4+x-3*x^3) / ((1-x)*(1+x)*(1+x^2)). - R. J. Mathar, Mar 10 2013

a(n+4) = a(n). - Alexander R. Povolotsky, Mar 15 2013

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

a(n) = 1/2+3*I^(2*n)/2+(1+I)*I^(-n)+(1-I)*I^n.

a(n) = (1+3*cos(n*Pi)+4*cos(n*Pi/2)+4*sin(n*Pi/2)+3*I*sin(n*Pi))/2. (End)

MAPLE

seq(op([4, 1, 0, -3]), n=0..40); # Wesley Ivan Hurt, Jul 09 2016

MATHEMATICA

PadRight[{}, 100, {4, 1, 0, -3}] (* or *) LinearRecurrence[{0, 0, 0, 1}, {4, 1, 0, -3}, 100] (* Harvey P. Dale, Nov 28 2014 *)

PROG

(MAGMA) for n in [0 .. 50] do (3*(-1)^n+1)/2 + 2*(-1)^((2*n-1+(-1)^n)/4); end for;

(MAGMA) &cat [[4, 1, 0, -3]^^30]; // Wesley Ivan Hurt, Jul 09 2016

(PARI) a(n)=[4, 1, 0, -3][n%4+1] \\ Charles R Greathouse IV, Jul 17 2016

CROSSREFS

Cf. A084100, A168361, A214864.

Sequence in context: A166073 A290724 A283879 * A122899 A223856 A153661

Adjacent sequences:  A216175 A216176 A216177 * A216179 A216180 A216181

KEYWORD

sign,easy

AUTHOR

Brad Clardy, Mar 10 2013

STATUS

approved

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Last modified May 27 21:52 EDT 2020. Contains 334671 sequences. (Running on oeis4.)