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A131714
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Period 6: repeat 1,-2,2,-1,2,-2.
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0
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1, -2, 2, -1, 2, -2, 1, -2, 2, -1, 2, -2, 1, -2, 2, -1, 2, -2, 1, -2, 2, -1, 2, -2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=(1/6)*{-3*(n mod 6)+4*[(n+1) mod 6]-3*[(n+2) mod 6]+3*[(n+3) mod 6]-4*[(n+4) mod 6]+3*[(n+5) mod 6]}, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Oct 02 2007
G.f.: (1-2*x+2*x^2)/(x+1)/(x^2-x+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 14 2007
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CROSSREFS
| Cf. A130196, A131556.
Sequence in context: A181810 A102297 A098398 * A130196 A158209 A119646
Adjacent sequences: A131711 A131712 A131713 * A131715 A131716 A131717
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KEYWORD
| sign
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Sep 14 2007
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