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A015850
Numbers k such that phi(k + 12) | sigma(k) for k not congruent to 0 (mod 3).
0
14, 23, 38, 109, 248, 280, 380, 406, 506, 1178, 1288, 1364, 1504, 1528, 1798, 1976, 1978, 1990, 2408, 2528, 2698, 3160, 3230, 4318, 4888, 6106, 6904, 7160, 7192, 7366, 8234, 8648, 8804, 8920, 8932, 9238, 10726, 10856, 11210, 11684, 11818, 12008, 12154, 14212
OFFSET
1,1
MATHEMATICA
Select[Range[1, 10000], Divisible[DivisorSigma[1, #], EulerPhi[12 + #]] && !Mod[#, 3] == 0 &] (* David Nacin, Mar 04 2012 *)
PROG
(PARI) is(n)=n%3 && sigma(n)%eulerphi(n+12)==0 \\ Charles R Greathouse IV, Sep 25 2012
CROSSREFS
Sequence in context: A010922 A010902 A010923 * A020905 A048635 A114872
KEYWORD
nonn
STATUS
approved