A132708 - OEIS

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A132708

Period 6: repeat [4, 2, 1, -4, -2, -1].

4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1, 4, 2, 1, -4, -2, -1

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OFFSET

0,1

COMMENTS

Old definition was: "First differences of 5^n mod 9".

LINKS

Table of n, a(n) for n=0..101.

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

FORMULA

G.f.: (x^2 + 2*x + 4)/(x^3 + 1). - Chai Wah Wu, Jun 04 2016

From Wesley Ivan Hurt, Jun 28 2016: (Start)

a(n) + a(n-3) = 0 for n>2.

a(n) = a(n-6) for n>5.

a(n) = cos(n*Pi) + 3*cos(n*Pi/3) + sqrt(3)*sin(n*Pi/3). (End)

MAPLE

A132708:= n -> [4, 2, 1, -4, -2, -1][(n mod 6)+1]: seq(A132708(n), n=0..100); # Wesley Ivan Hurt, Jun 28 2016

MATHEMATICA

PadRight[{}, 120, {4, 2, 1, -4, -2, -1}] (* Harvey P. Dale, Nov 21 2015 *)

Differences[PowerMod[5, Range[0, 90], 9]] (* Alonso del Arte, Jun 04 2016 *)

PROG

(Magma) &cat [[4, 2, 1, -4, -2, -1]^^30]; // Wesley Ivan Hurt, Jun 28 2016

CROSSREFS

Cf. A070366 (5^n mod 9).

Sequence in context: A023526 A082901 A136619 * A153727 A349245 A356631

Adjacent sequences: A132705 A132706 A132707 * A132709 A132710 A132711

KEYWORD

sign,easy

AUTHOR

Paul Curtz, Nov 16 2007

EXTENSIONS

Name changed by Wesley Ivan Hurt, Jun 28 2016

STATUS

approved