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A015781 Phi(n) + 2 | sigma(n + 2). 4

%I #16 Dec 10 2018 17:12:54

%S 4,8,12,22,26,32,42,54,118,145,230,340,342,363,512,528,3840,4678,4930,

%T 14526,15906,18768,23274,25134,26206,26588,36663,45368,53328,131072,

%U 168566,281535,304270,523774,526080,875520,2115600,5531768,20427262,32294122,33665022,55328382,301046166

%N Phi(n) + 2 | sigma(n + 2).

%t Select[Range[1000000], Divisible[DivisorSigma[1, # + 2], EulerPhi[#] + 2] &] (* _Amiram Eldar_, Dec 10 2018 *)

%o (PARI) is(n)=!(sigma(n+2)%(eulerphi(n)+2)) \\ _Charles R Greathouse IV_, Sep 25 2012

%Y CF. A015775.

%K nonn

%O 1,1

%A _Robert G. Wilson v_

%E Corrected by _Charles R Greathouse IV_, Sep 25 2012

%E Incorrect a(1)=1 removed and more terms from _Sean A. Irvine_, Dec 10 2018

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Last modified September 14 16:47 EDT 2024. Contains 375929 sequences. (Running on oeis4.)