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A079536
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a(n) = phi(n)*d(n) - sigma(n).
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3
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0, -1, 0, -1, 2, -4, 4, 1, 5, -2, 8, -4, 10, 0, 8, 9, 14, -3, 16, 6, 16, 4, 20, 4, 29, 6, 32, 16, 26, -8, 28, 33, 32, 10, 48, 17, 34, 12, 40, 38, 38, 0, 40, 36, 66, 16, 44, 36, 69, 27, 56, 46, 50, 24, 88, 72, 64, 22, 56, 24, 58, 24, 112, 97, 108, 16, 64, 66, 80, 48, 68, 93, 70, 30, 116, 76, 144
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OFFSET
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1,5
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COMMENTS
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It is known that a(n) >= 0 if n is odd
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REFERENCES
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D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 10.
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LINKS
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MATHEMATICA
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Table[EulerPhi[n]*DivisorSigma[0, n] - DivisorSigma[1, n], {n, 1, 80}] (* G. C. Greubel, Jan 14 2019 *)
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PROG
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(PARI) vector(80, n, eulerphi(n)*sigma(n, 0) - sigma(n, 1)) \\ G. C. Greubel, Jan 14 2019
(Magma) [EulerPhi(n)*DivisorSigma(0, n) - DivisorSigma(1, n): n in [1..80]]; // G. C. Greubel, Jan 14 2019
(Sage) [euler_phi(n)*sigma(n, 0) - sigma(n, 1) for n in (1..80)] # G. C. Greubel, Jan 14 2019
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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