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URL: https://oeis.org/A132367

⇱ A132367 - OEIS

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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
OFFSET
0,3
COMMENTS
Nonsimple continued fraction expansion of 1+1/sqrt(3) = 1 + A020760. - R. J. Mathar, Mar 08 2012
FORMULA
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
KEYWORD
sign,easy,less
AUTHOR
Paul Curtz, Nov 09 2007
STATUS
approved