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A132429
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Period 4: repeat 3, 1, -1, -3.
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3
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3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1, -1, -3, 3, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Differences: -2*(1, 1, 1, -3).
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LINKS
| Index entries for sequences related to linear recurrences with constant coefficients, signature (-1,-1,-1).
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FORMULA
| a(n) = (1/2)*(-3*(n mod 4)+((n+1) mod 4)+((n+2) mod 4)+((n+3) mod 4)). - Paolo P. Lava, Nov 19 2007
G.f.: (3+4*x+3*x^2)/((1+x)*(1+x^2)). - Jaume Oliver Lafont, Aug 30 2009
a(n) = (1-I)*I^n+(-1)^n+(1+I)*(-I)^n, with I=sqrt(-1). - Paolo P. Lava, May 04 2010
a(n) = (2-(-1)^n)*(-1)^((n-1)*n/2). - Bruno Berselli, Sep 29 2011
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MATHEMATICA
| PadRight[{}, 104, {3, 1, -1, -3}] (* From Harvey P. Dale, Nov 12 2011 *)
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PROG
| (PARI) a(n)=3-2*(n%4) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Aug 28 2009]
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CROSSREFS
| Cf. A084101 (1, 3, 3, 1).
Sequence in context: A033989 A169941 A099545 * A046540 A123191 A157454
Adjacent sequences: A132426 A132427 A132428 * A132430 A132431 A132432
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KEYWORD
| sign,easy
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Nov 13 2007
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