OFFSET
1,2
COMMENTS
Coincides with A073539 in the first 850000 terms and possibly more. - R. J. Mathar, Sep 08 2008
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..20000
Vaclav Kotesovec, Plot of a(n)/n^2 and a(n)/(n^2/log(n)) for n = 1..20000
FORMULA
a(n) seems to be asymptotic to c*n^2 with c = 0.1....
MATHEMATICA
Select[Range[1000], Divisible[EulerPhi[#]^2, #]&] (* Vaclav Kotesovec, Feb 16 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 08 2004
STATUS
approved