OFFSET
1,2
LINKS
Wikipedia, Radical of an integer.
EXAMPLE
a(4) = 100; a(4) = Sum_{k=1..4} 4^rad(k) = 4^rad(1) + 4^rad(2) + 4^rad(3) + 4^rad(4) = 4^1 + 4^2 + 4^3 + 4^2 = 100.
MATHEMATICA
a[n_] := Sum[n^Times @@ FactorInteger[k][[;; , 1]], {k, 1, n}]; Array[a, 20] (* Amiram Eldar, Feb 01 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jan 30 2022
STATUS
approved