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Search: id:A128016
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| A128016 |
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Expansion of (1+x+x^2+x^3)/(1-x^2+x^4). |
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+0
2
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| 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Periodic{1,1,2,2,1,1,-1,-1,-2,-2,-1,-1}.
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FORMULA
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G.f.: (1-x^4)/(1-x-x^2+x^3+x^4-x^5); a(n)=cos(5*pi*n/6)/2+(1-sqrt(3)/2)sin(5*pi*n/6)+cos(pi*n/6)/2+(1+sqrt(3)/2)sin(pi*n/6);
a(n)=(1/12)*{-2*[n mod 12]-[(n+2) mod 12]+[(n+4) mod 12]+2*[(n+6) mod 12]+[(n+8) mod 12]-[(n+10) mod 12]}, with n>=0. - Paolo P. Lava (ppl(AT)spl.at), Jun 01 2007
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CROSSREFS
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Cf. A128017.
Sequence in context: A085301 A138385 A030614 this_sequence A128017 A096285 A121561
Adjacent sequences: A128013 A128014 A128015 this_sequence A128017 A128018 A128019
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Feb 11 2007
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