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A079530
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a(n) = phi(n) - ceiling(sqrt(n)).
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7
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0, -1, 0, 0, 1, -1, 3, 1, 3, 0, 6, 0, 8, 2, 4, 4, 11, 1, 13, 3, 7, 5, 17, 3, 15, 6, 12, 6, 22, 2, 24, 10, 14, 10, 18, 6, 29, 11, 17, 9, 33, 5, 35, 13, 17, 15, 39, 9, 35, 12, 24, 16, 44, 10, 32, 16, 28, 20, 50, 8, 52, 22, 28, 24, 39, 11, 57, 23, 35, 15, 61, 15, 63, 27, 31, 27, 51, 15, 69, 23, 45
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OFFSET
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1,7
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COMMENTS
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a(n) >= 0 except for n = 2 and 6.
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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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EXAMPLE
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a(6) = phi(6) - ceiling(sqrt(6)) = 2 - 3 = -1.
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MAPLE
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MATHEMATICA
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Table[EulerPhi[n] - Ceiling[Sqrt[n]], {n, 100}] (* Wesley Ivan Hurt, Nov 01 2013 *)
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PROG
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(Magma) [EulerPhi(n) - Ceiling(Sqrt(n)): n in [1..100]]; // G. C. Greubel, Jan 14 2019
(Sage) [euler_phi(n) - ceil(sqrt(n)) for n in (1..100)] # G. C. Greubel, Jan 14 2019
(Python)
from math import isqrt
from sympy import totient
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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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