OFFSET
2,4
COMMENTS
It is known that a(n) >= 0.
REFERENCES
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 9.
LINKS
G. C. Greubel, Table of n, a(n) for n = 2..10000
MATHEMATICA
Table[EulerPhi[n] - Ceiling[n*Log[2.]/(2*Log[n])], {n, 2, 80}] (* G. C. Greubel, Jan 14 2019 *)
PROG
(PARI) vector(80, n, n++; eulerphi(n) - ceil(n*log(2.)/(2*log(n)))) \\ G. C. Greubel, Jan 14 2019
(Magma) [EulerPhi(n) - Ceiling(n*Log(2.)/(2*Log(n))): n in [2..80]]; // G. C. Greubel, Jan 14 2019
(Sage) [euler_phi(n) - ceil(n*log(2.)/(2*log(n))) for n in (2..80)] # G. C. Greubel, Jan 14 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 23 2003
STATUS
approved