OFFSET
1,3
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
MATHEMATICA
rad[n_] := Times @@ (First /@ FactorInteger@n);
a[n_] := GCD[n - rad[n], DivisorSigma[1, n] - rad[n] - n];
Array[a, 100] (* Jean-François Alcover, Dec 01 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 09 2019
STATUS
approved