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A089266
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Rational knots of determinant 2n+1, counting chiral pairs twice.
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1
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2, 3, 4, 4, 6, 7, 6, 9, 10, 8, 12, 11, 10, 15, 16, 12, 14, 19, 14, 21, 22, 14, 24, 22, 18, 27, 22, 20, 30, 31, 20, 26, 34, 24, 36, 37, 22, 32, 40, 28, 42, 34, 30, 45, 38, 32, 38, 49, 32, 51, 52, 28, 54, 55, 38, 57, 46, 38, 50, 56, 42, 51, 64, 44, 66, 56
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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a[n_] := (EulerPhi[2*n+1] + 2^PrimeNu[2*n+1])/2; Table[a[n], {n, 1, 66}] (* Jean-François Alcover, Oct 11 2013, after Pari *)
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PROG
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(PARI) a(n)=(eulerphi(2*n+1)+2^omega(2*n+1))/2
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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STATUS
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approved
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