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A015781
Phi(n) + 2 | sigma(n + 2).
4
4, 8, 12, 22, 26, 32, 42, 54, 118, 145, 230, 340, 342, 363, 512, 528, 3840, 4678, 4930, 14526, 15906, 18768, 23274, 25134, 26206, 26588, 36663, 45368, 53328, 131072, 168566, 281535, 304270, 523774, 526080, 875520, 2115600, 5531768, 20427262, 32294122, 33665022, 55328382, 301046166
OFFSET
1,1
MATHEMATICA
Select[Range[1000000], Divisible[DivisorSigma[1, # + 2], EulerPhi[#] + 2] &] (* Amiram Eldar, Dec 10 2018 *)
PROG
(PARI) is(n)=!(sigma(n+2)%(eulerphi(n)+2)) \\ Charles R Greathouse IV, Sep 25 2012
CROSSREFS
CF. A015775.
Sequence in context: A188293 A128233 A092108 * A130643 A014617 A239053
KEYWORD
nonn
EXTENSIONS
Corrected by Charles R Greathouse IV, Sep 25 2012
Incorrect a(1)=1 removed and more terms from Sean A. Irvine, Dec 10 2018
STATUS
approved