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Search: id:A131720
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| A131720 |
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Period 6: repeat 0,1,-1,1,-1,0. |
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+0
2
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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; listen)
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OFFSET
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0,1
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FORMULA
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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 (ppl(AT)spl.at), 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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CROSSREFS
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Sequence in context: A099859 A102460 A080908 this_sequence A131719 A100656 A053867
Adjacent sequences: A131717 A131718 A131719 this_sequence A131721 A131722 A131723
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KEYWORD
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sign
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AUTHOR
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Paul Curtz (bpcrtz(AT)free.fr), Sep 15 2007
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