A109658 - OEIS

%I #12 Oct 06 2018 04:38:53

%S 1,2,3,9,11,18,54,74,108,135,426,531,585,1361,3456,6771,7245,7392,

%T 11025,11957,21494,27063,41952,68494,72516,108742,128331

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

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

%t Do[s = n^DivisorSigma[1, n]; k = Plus @@ IntegerDigits[s]; If[Mod[k, n] == 0, Print[n]], {n, 1, 10000}]

%t Select[Range[150000],Divisible[Total[IntegerDigits[#^DivisorSigma[ 1,#]]],#]&] (* _Harvey P. Dale_, Jul 19 2013 *)

%K base,nonn,more

%O 1,2

%A _Ryan Propper_, Aug 06 2005

%E More terms from _Ryan Propper_, Oct 10 2005

%E More terms from _Harvey P. Dale_, Jul 19 2013