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A131756 Period 3: repeat [2, -1, 3]. 1
2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3, 2, -1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..104.

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

FORMULA

a(n) = (1/9)*{7*(n mod 3)-8*[(n+1) mod 3]+13*[(n+3) mod 3]}. - Paolo P. Lava, Oct 08 2007

a(n) = 4/3+2/3*cos(2/3*Pi*n)-4/3*3^(1/2)*sin(2/3*Pi*n). - R. J. Mathar, Nov 15 2007

G.f.: (2-x+3*x^2)/(1-x^3). - Jaume Oliver Lafont, Mar 24 2009

a(n) = a(n-3) for n>2. - Wesley Ivan Hurt, Jul 01 2016

MAPLE

seq(op([2, -1, 3]), n=0..50); # Wesley Ivan Hurt, Jul 01 2016

MATHEMATICA

PadRight[{}, 100, {2, -1, 3}] (* Wesley Ivan Hurt, Jul 01 2016 *)

PROG

(PARI) a(n)=[2, -1, 3][1+n%3] \\ Jaume Oliver Lafont, Mar 24 2009

(MAGMA) &cat [[2, -1, 3]^^30]; // Wesley Ivan Hurt, Jul 01 2016

CROSSREFS

Cf. A130784.

Sequence in context: A118123 A181743 A174737 * A212620 A194859 A194838

Adjacent sequences:  A131753 A131754 A131755 * A131757 A131758 A131759

KEYWORD

sign,easy

AUTHOR

Paul Curtz, Oct 04 2007

STATUS

approved

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Last modified May 24 18:18 EDT 2017. Contains 286997 sequences.