OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
rad[n_] := Product[fa[n][[i, 1]], {i, Length[fa[n]]}]; fa = FactorInteger; Select[Range[500], rad[EulerPhi[#]] > EulerPhi[rad[#]] &]
PROG
(PARI) rad(n)=my(f=factor(n)[, 1]); prod(i=1, #f, f[i])
is(n)=rad(eulerphi(n))>eulerphi(rad(n)) \\ Charles R Greathouse IV, Dec 27 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
José María Grau Ribas, Jun 05 2013
STATUS
approved