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A199167 Smallest number k such that the sum of the n-th powers of the divisors of k is divisible by n. 2
1, 3, 2, 15, 8, 12, 4, 105, 2, 3, 43, 60, 9, 12, 8, 945, 67, 300, 37, 240, 5, 48, 137, 420, 8, 5, 2, 60, 173, 12, 16, 10395, 86, 13, 76, 2100, 73, 147, 8, 1680, 163, 4800, 257, 240, 8, 3072, 281, 3780, 4, 3, 101, 60, 211, 14700, 8, 420, 32, 17, 353, 8400, 169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..200

EXAMPLE

a(6) = 12 because the divisors of 12 are 1, 2, 3, 4, 6, 12 and 1^6 + 2^6 + 3^6 + 4^6 + 6^6 + 12^6 =  3037530 = 6*506255.

MAPLE

with(numtheory):

a:= proc(n) local k;

      for k while irem (add (d &^n mod n, d=divisors(k)), n)<>0

      do od; k

    end:

seq (a(n), n=1..63);

MATHEMATICA

snk[n_]:=Module[{k=1}, While[!Divisible[DivisorSigma[n, k], n], k++]; k]; Array[ snk, 70] (* Harvey P. Dale, Jun 07 2016 *)

PROG

(PARI) a(n)=my(k); while(sigma(k++, n)%n, ); k \\ Charles R Greathouse IV, Nov 03 2011

CROSSREFS

Cf. A066135.

Sequence in context: A072346 A103236 A141235 * A218969 A185973 A258566

Adjacent sequences:  A199164 A199165 A199166 * A199168 A199169 A199170

KEYWORD

nonn

AUTHOR

Michel Lagneau, Nov 03 2011

STATUS

approved

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Last modified February 28 04:39 EST 2020. Contains 332321 sequences. (Running on oeis4.)