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A133186
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Period 4: repeat 1, 2, 1, -4.
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0
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1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=(1/4)*{-5*(n mod 4)+5*[(n+1) mod 4]+[(n+2) mod 4]-[(n+3) mod 4]}, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Oct 24 2007
a(n)=-[(3/2)*I]*I^n+(-1)^n+[(3/2)*I]*(-I)^n, with n>=0 and I=sqrt(-1) - Paolo P. Lava (paoloplava(AT)gmail.com), Jul 17 2008
G.f.: 1/(1+x)+3x/(1+x^2). a(n)=(-1)^n+3*A056594(n-1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 30 2008]
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CROSSREFS
| Cf. A109008.
Sequence in context: A086256 A057550 A059150 * A084236 A068057 A003484
Adjacent sequences: A133183 A133184 A133185 * A133187 A133188 A133189
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KEYWORD
| sign
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Oct 07 2007
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