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A014695
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Poincaré series [or Poincare series] (or Molien series) for mod 2 cohomology of Q_8.
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19
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1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1
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OFFSET
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0,2
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COMMENTS
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Periodic sequence: Repeat 1, 2, 2, 1.
Continued fraction expansion of (5+sqrt(221))/14.
Decimal expansion of 37/303. (End)
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LINKS
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FORMULA
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G.f.: (1+x+x^2)/((1-x)*(1+x^2)) = (1+2*x+2*x^2+x^3)/(1-x^4).
a(n) = (6-(1+i)*i^n-(1-i)*(-i)^n)/4 where i = sqrt(-1). - Klaus Brockhaus, May 14 2010
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MATHEMATICA
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LinearRecurrence[{1, -1, 1}, {1, 2, 2}, 120] (* Harvey P. Dale, Jan 19 2020 *)
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PROG
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(PARI) x='x+O('x^100); Vec((1+2*x+2*x^2+x^3)/(1-x^4)) \\ Altug Alkan, Dec 24 2015
(Python)
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CROSSREFS
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Denominators for the sequence whose numerators are A064038.
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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