login
A109668
Numbers n such that the sum of the digits of phi(n)^sigma(n) is divisible by n.
0
1, 9, 18, 35, 67, 189, 310, 475, 516, 684, 2493, 2527, 3465, 4701, 5157, 8321, 11403, 11780, 14709, 18396, 47250, 124385, 131952, 280342, 288820, 304299, 525195, 536756, 899703
OFFSET
1,2
EXAMPLE
The digits of phi(3465)^sigma(3465) sum to 72765 and 72765 is divisible by 3465, so 3465 is in the sequence.
MATHEMATICA
Do[s = EulerPhi[n]^DivisorSigma[1, n]; k = Plus @@ IntegerDigits[s]; If[Mod[k, n] == 0, Print[n]], {n, 1, 10^4}]
Select[Range[50000], Divisible[Total[IntegerDigits[EulerPhi[#]^ DivisorSigma[1, #]]], #]&] (* Harvey P. Dale, Mar 19 2011 *)
CROSSREFS
Sequence in context: A221533 A139591 A191268 * A234598 A051063 A173942
KEYWORD
base,more,nonn
AUTHOR
Ryan Propper, Aug 06 2005
EXTENSIONS
More terms from Harvey P. Dale, Mar 19 2011
a(22)-a(29) from Lars Blomberg, Dec 02 2016
STATUS
approved