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

17296, 24016, 334144656, 358585488, 2955423888, 311063879024

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..6.

Example

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

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);

Crossrefs

Cf. A003415, A229342, A230165, A342021.

Sequence in context: A093790 A229683 A228379 * A001381 A219357 A219325

Adjacent sequences: A230161 A230162 A230163 * A230165 A230166 A230167

Keyword

nonn,more

Author

Paolo P. Lava, Oct 14 2013

Extensions

a(3)-a(5) from Giovanni Resta, Oct 14 2013

a(6) from Giovanni Resta, Mar 11 2014

Status

approved