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A131720
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Period 6: repeat 0,1,-1,1,-1,0.
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1
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0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, -1, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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LINKS
| Index entries for sequences related to linear recurrences with constant coefficients, signature (-1,-1,-1,-1,-1).
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FORMULA
| a(n)=(1/6)*{-[(n+1) mod 6]+2*[(n+2) mod 6]-2*[(n+3) mod 6]+2*[(n+4) mod 6]-[(n+5) mod 6]}, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Oct 02 2007
a(n) = 1/6*cos(1/3*Pi*n)+1/6*3^(1/2)*sin(1/3*Pi*n)+1/2*cos(2/3*Pi*n)+1/6*3^(1/2)*sin(2/3*Pi*n)+2/3*(-1)^(1+n). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 15 2007
G.f.:(x*(x^2+1))/((x+1)*(x^2-x+1)*(x^2+x+1)) [From Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009]
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PROG
| (PARI) a(n)=[0, 1, -1, 1, -1, 0][n%6+1] \\ Charles R Greathouse IV, Jun 02 2011
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CROSSREFS
| Sequence in context: A176416 A102460 A080908 * A131719 A100656 A053867
Adjacent sequences: A131717 A131718 A131719 * A131721 A131722 A131723
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KEYWORD
| sign,easy,less
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Sep 15 2007
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