OFFSET
1,1
COMMENTS
Numbers k such that rad(nusigma(k)) = rad(k), where rad(k) is the squarefree kernel of k (A007947).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
rad[n_] := Times @@ (First@# & /@ FactorInteger@ n); usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); nusigma[n_] := DivisorSigma[1, n] - usigma[n]; Select[Range[10^4], rad[nusigma[#]] == rad[#] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Nov 23 2019
STATUS
approved