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A063070
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a(n) = phi(n) - d(n), where d(n) is the number of divisors function (A000005).
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9
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0, -1, 0, -1, 2, -2, 4, 0, 3, 0, 8, -2, 10, 2, 4, 3, 14, 0, 16, 2, 8, 6, 20, 0, 17, 8, 14, 6, 26, 0, 28, 10, 16, 12, 20, 3, 34, 14, 20, 8, 38, 4, 40, 14, 18, 18, 44, 6, 39, 14, 28, 18, 50, 10, 36, 16, 32, 24, 56, 4, 58, 26, 30, 25, 44, 12, 64, 26, 40, 16, 68, 12, 70, 32, 34, 30, 56, 16, 76, 22, 49, 36, 80, 12, 60, 38, 52, 32, 86, 12, 68, 38
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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) >= 1 for n >= 31.
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REFERENCES
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D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 11.
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LINKS
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FORMULA
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MATHEMATICA
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Table[EulerPhi[n] - DivisorSigma[0, n], {n, 100}] (* Wesley Ivan Hurt, Nov 24 2021 *)
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PROG
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(PARI) j=[]; for(n=1, 150, j=concat(j, eulerphi(n)-(numdiv(n)))); j
(PARI) { for (n=1, 1000, write("b063070.txt", n, " ", eulerphi(n) - numdiv(n)) ) } \\ Harry J. Smith, Aug 16 2009
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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STATUS
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approved
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