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A158678
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Period 18: repeat 0,0,0,3,0,0,0,3,0,-3,0,3,0,-3,0,0,0,-3.
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0
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0, 0, 0, 3, 0, 0, 0, 3, 0, -3, 0, 3, 0, -3, 0, 0, 0, -3, 0, 0, 0, 3, 0, 0, 0, 3, 0, -3, 0, 3, 0, -3, 0, 0, 0, -3, 0, 0, 0, 3, 0, 0, 0, 3, 0, -3, 0, 3, 0, -3, 0, 0, 0, -3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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FORMULA
| a(n) = A158674(n) - A158677(n) = a(n-18).
a(n)=(1/6)*{-(n mod 18)+[(n+1) mod 18]-[(n+4) mod 18]+[(n+5) mod 18]+[(n+6) mod 18]-[(n+7) mod 18]-[(n+8) mod 18]+[(n+9) mod 18]+[(n+10) mod 18]-[(n+11) mod 18]+[(n+14) mod 18]-[(n+15) mod 18]}, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Mar 27 2009]
G.f.: 3*(1+x+x^2)*(x^2-x+1)*(x^4-x^2+1)*x^4/((x^6-x^3+1)*(x^6+x^3+1)). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 08 2009
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CROSSREFS
| Sequence in context: A090225 A206705 A200221 * A117980 A065032 A007514
Adjacent sequences: A158675 A158676 A158677 * A158679 A158680 A158681
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KEYWORD
| sign,easy
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Mar 24 2009
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EXTENSIONS
| Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 08 2009
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