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A015786
Numbers k such that phi(k) + 7 | sigma(k + 7).
3
3, 42, 162, 5478, 491910, 45504705, 175271190, 227418362790
OFFSET
1,1
EXAMPLE
42 is a term in the sequence since phi(42) + 7 = 12 + 7 = 19 divides sigma(42 + 7) = 57.
MATHEMATICA
Select[Range[1000000], Divisible[DivisorSigma[1, # + 7], EulerPhi[#] + 7] &] (* Amiram Eldar, Dec 10 2018 *)
PROG
(PARI) is(n)=!(sigma(n+7)%(eulerphi(n)+7)) \\ Charles R Greathouse IV, Sep 25 2012
KEYWORD
nonn,more
EXTENSIONS
Corrected and a(5)-a(6) added by Charles R Greathouse IV, Sep 25 2012
a(7) from Sean A. Irvine, Dec 10 2018
a(8) from Kevin P. Thompson, Jul 23 2022
STATUS
approved