A230164 Numbers k such that k' = sigma(k), where k' is the arithmetic derivative of k.

17296, 24016, 334144656, 358585488, 2955423888, 311063879024

Offset: 1

Author

Paolo P. Lava, Oct 14 2013

Keywords

• nonn
• more

Comments

a(7) > 10^12. - Giovanni Resta, Mar 11 2014

Examples

			If k = 17296 then k' = sigma(k) = 35712. If k = 24016 then k' = sigma(k) = 49600.
		

Crossrefs

Cf. A003415, A229342, A230165, A342021.

Programs

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