A109658 Numbers k such that the sum of the digits of k^sigma(k) is divisible by k.

1, 2, 3, 9, 11, 18, 54, 74, 108, 135, 426, 531, 585, 1361, 3456, 6771, 7245, 7392, 11025, 11957, 21494, 27063, 41952, 68494, 72516, 108742, 128331

Offset

1,2

Links

Table of n, a(n) for n=1..27.

Example

The sum of the digits of 531^sigma(531) is 9558 and 9558 is divisible by 531, so 531 is in the sequence.

Mathematica

Do[s = n^DivisorSigma[1, n]; k = Plus @@ IntegerDigits[s]; If[Mod[k, n] == 0, Print[n]], {n, 1, 10000}]
Select[Range[150000], Divisible[Total[IntegerDigits[#^DivisorSigma[ 1, #]]], #]&] (* Harvey P. Dale, Jul 19 2013 *)

Crossrefs

Sequence in context: A110772 A074338 A111319 * A257027 A271548 A369338

Adjacent sequences: A109655 A109656 A109657 * A109659 A109660 A109661

Keyword

base,nonn,more

Author

Ryan Propper, Aug 06 2005

Extensions

More terms from Ryan Propper, Oct 10 2005

More terms from Harvey P. Dale, Jul 19 2013

Status

approved