

A079531


a(n) = phi(n)  ceiling(n^(2/3)).


5



0, 1, 1, 1, 1, 2, 2, 0, 1, 1, 5, 2, 6, 0, 1, 1, 9, 1, 10, 0, 4, 2, 13, 1, 11, 3, 9, 2, 18, 2, 20, 5, 9, 5, 13, 1, 24, 6, 12, 4, 28, 1, 29, 7, 11, 9, 32, 2, 28, 6, 18, 10, 37, 3, 25, 9, 21, 13, 42, 0, 44, 14, 20, 16, 31, 3, 49, 15, 27, 7, 52, 6, 54, 18, 22, 18, 41, 5, 59, 13, 35, 21, 62, 4, 44, 22
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OFFSET

1,6


COMMENTS

a(n) >= 0 for n > 30.


REFERENCES

D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 9.


LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000


MATHEMATICA

Table[EulerPhi[n]Ceiling[Surd[n, 3]^2], {n, 90}] (* Harvey P. Dale, Oct 27 2016 *)


PROG

(PARI) a(n)=eulerphi(n)sqrtnint(n^21, 3)1 \\ Charles R Greathouse IV, Feb 07 2013
(MAGMA) [EulerPhi(n)  Ceiling(n^(2/3)): n in [1..100]]; // G. C. Greubel, Jan 14 2019
(Sage) [euler_phi(n)  ceil(n^(2/3)) for n in (1..100)] # G. C. Greubel, Jan 14 2019


CROSSREFS

Cf. A000010, A079530, A079532, A079534.
Sequence in context: A174626 A264909 A104579 * A182882 A134178 A059018
Adjacent sequences: A079528 A079529 A079530 * A079532 A079533 A079534


KEYWORD

sign,easy


AUTHOR

N. J. A. Sloane, Jan 23 2003


STATUS

approved



