OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1052 (terms below 5*10^10)
EXAMPLE
12 is in the sequence since 12 = 2^2 * 3 and uphi(12) = 6 = 2 * 3 both have the same set of prime divisors, {2, 3}.
MATHEMATICA
rad[n_] := Times @@ (First@# & /@ FactorInteger@ n); uphi[1] = 1; uphi[n_] := Times @@ (-1 + Power @@@ FactorInteger[n]); Select[Range[10^5], rad[#] == rad[uphi[#]] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Nov 22 2019
STATUS
approved