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%I #6 Feb 01 2022 08:56:30
%S 1,6,39,100,3305,54726,958447,2392776,5375169,10011102310,
%T 311270518031,804967791420,304805198256481,11910060539653290,
%U 469042238075266815,1229501390272865296,830281003630789139585,2193053904527215207698,1983916064827419873906079
%N a(n) = Sum_{k=1..n} n^rad(k).
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Radical_of_an_integer">Radical of an integer</a>.
%e 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.
%t a[n_] := Sum[n^Times @@ FactorInteger[k][[;; , 1]], {k, 1, n}]; Array[a, 20] (* _Amiram Eldar_, Feb 01 2022 *)
%Y Cf. A007947 (rad), A176031, A350996.
%K nonn
%O 1,2
%A _Wesley Ivan Hurt_, Jan 30 2022