OFFSET
1,2
COMMENTS
LINKS
David A. Corneth, Table of n, a(n) for n = 1..12173 (terms <= 10^15)
EXAMPLE
For 80, phi(80) = 32, tau(80) = 10 and tau(80)*phi(80)/80 = 4, hence 80 is a term.
MAPLE
with(numtheory):
filter:= m-> irem(phi(m)*tau(m), m)=0:
select(filter, [$1..7000])[];
MATHEMATICA
Select[Range[7000], Divisible[DivisorSigma[0, #] * EulerPhi[#], #] &] (* Amiram Eldar, Aug 01 2020 *)
PROG
(PARI) isok(m) = (eulerphi(m)*numdiv(m) % m) == 0; \\ Michel Marcus, Aug 02 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Bernard Schott, Aug 01 2020
STATUS
approved