A230164 Numbers k such that k' = sigma(k), where k' is the arithmetic derivative of k.
17296, 24016, 334144656, 358585488, 2955423888, 311063879024
Offset: 1
Examples
If k = 17296 then k' = sigma(k) = 35712. If k = 24016 then k' = sigma(k) = 49600.
Programs
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Maple
with(numtheory); P:= proc(q) local a,n,p; for n from 1 to q do a:=n*add(op(2,p)/op(1,p),p=ifactors(n)[2]); if sigma(n)=a then print(n); fi; od; end: P(10^9);
Extensions
a(3)-a(5) from Giovanni Resta, Oct 14 2013
a(6) from Giovanni Resta, Mar 11 2014
Comments