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A097604
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a(n) = floor( phi(n)*sqrt(2*n) ) - n.
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2
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0, 0, 1, 1, 7, 0, 15, 8, 16, 7, 35, 7, 48, 17, 28, 29, 76, 18, 91, 30, 56, 44, 126, 31, 116, 60, 105, 61, 184, 31, 205, 96, 129, 97, 165, 65, 272, 118, 172, 103, 321, 67, 346, 143, 182, 165, 398, 108, 366, 150, 272, 192, 482, 133, 364, 197, 327, 243, 571, 115, 601, 272, 341
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OFFSET
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1,5
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COMMENTS
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This is known to be always >= 0, i.e. that n/phi(n) <= sqrt(2n) holds for all n. This is a consequence of the stronger inequality in A079530.
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REFERENCES
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D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 9.
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LINKS
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MATHEMATICA
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Table[Floor[Sqrt[2*n]*EulerPhi[n]] - n, {n, 1, 100}] (* G. C. Greubel, Jan 14 2019 *)
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PROG
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(PARI) vector(100, n, (sqrt(2*n)*eulerphi(n))\1 -n) \\ G. C. Greubel, Jan 14 2019
(Magma) [Floor(Sqrt(2*n)*EulerPhi(n)) - n: n in [1..100]]; // G. C. Greubel, Jan 14 2019
(Sage) [floor(sqrt(2*n)*euler_phi(n)) - n for n in (1..100)] # G. C. Greubel, Jan 14 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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