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A132367 Period 6: repeat [1, 1, 2, -1, -1, -2]. 5
1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2, 1, 1, 2, -1, -1, -2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Nonsimple continued fraction expansion of 1+1/sqrt(3) = 1 + A020760. - R. J. Mathar, Mar 08 2012

LINKS

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

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

FORMULA

a(n) = (1/6)*{-3*(n mod 6)+[(n+1) mod 6]+3*[(n+3) mod 6]-[(n+4) mod 6]}. - Paolo P. Lava, Nov 19 2007

a(n) = cos(Pi*n/3)/3+sqrt(3)*sin(Pi*n/3)+2*(-1)^n/3. - R. J. Mathar, Oct 08 2011

From Wesley Ivan Hurt, Jun 19 2016: (Start)

G.f.: (1+x+2*x^2)/(1+x^3).

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

MAPLE

A132367:=n->[1, 1, 2, -1, -1, -2][(n mod 6)+1]: seq(A132367(n), n=0..100); # Wesley Ivan Hurt, Jun 19 2016

MATHEMATICA

PadRight[{}, 120, {1, 1, 2, -1, -1, -2}] (* Harvey P. Dale, Jul 28 2012 *)

PROG

(PARI) a(n)=[1, 1, 2, -1, -1, -2][n%6+1] \\ Charles R Greathouse IV, Jun 02 2011

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

CROSSREFS

Cf. A020760, A061347, A100051, A100063, A122876.

Sequence in context: A132419 A131556 A107751 * A087204 A101825 A177702

Adjacent sequences:  A132364 A132365 A132366 * A132368 A132369 A132370

KEYWORD

sign,easy,less

AUTHOR

Paul Curtz, Nov 09 2007

STATUS

approved

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Last modified June 4 01:05 EDT 2020. Contains 334808 sequences. (Running on oeis4.)