OFFSET
1,5
COMMENTS
It is known that a(n) >= 0.
REFERENCES
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 9.
W. Sierpiński, Elementary Theory of Numbers. Państ. Wydaw. Nauk., Warsaw, 1964.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
W. Sierpiński, Elementary Theory of Numbers, Warszawa 1964.
MAPLE
f:= proc(n) if not isprime(n) then floor(n - sqrt(n)) - numtheory:-phi(n) fi end proc:
map(f, [$4..200]); # Robert Israel, Nov 09 2023
PROG
(PARI) lista(nn) = forcomposite(n=1, nn, print1(floor(n - sqrt(n)) - eulerphi(n), ", ")); \\ Michel Marcus, Dec 12 2014
CROSSREFS
KEYWORD
nonn,look
AUTHOR
N. J. A. Sloane, Jan 23 2003
STATUS
approved