OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..435 (terms below 5*10^10)
EXAMPLE
6 is in the sequence since 6 = 2 * 3 and usigma(6) = 12 = 2^2 * 3 both have the same set of prime divisors, {2, 3}.
MATHEMATICA
rad[n_] := Times @@ (First@# & /@ FactorInteger@ n); usigma[1]=1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); Select[Range[2*10^5], rad[#] == rad[usigma[#]] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Nov 22 2019
STATUS
approved