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A015787 Numbers n such that phi(n) + 8 | sigma(n + 8), where phi = A000010 and sigma = A000203. 1

%I #14 Jul 24 2020 01:47:44

%S 2,18,22,34,46,48,58,94,106,132,150,166,178,180,187,214,274,346,358,

%T 394,448,466,488,526,550,562,616,624,634,660,664,744,756,772,778,782,

%U 790,798,884,886,898,934,1138,1174,1186,1354,1366,1438,1618

%N Numbers n such that phi(n) + 8 | sigma(n + 8), where phi = A000010 and sigma = A000203.

%C From _Robert Israel_, Jul 23 2020: (Start)

%C The first odd terms are 187, 2407, 98587, 388315.

%C If p > 5 is in A228353 then 2*p is in the sequence. (End)

%H Robert Israel, <a href="/A015787/b015787.txt">Table of n, a(n) for n = 1..10000</a>

%p select(t -> numtheory:-sigma(t+8) mod (numtheory:-phi(t)+8)=0, [$1..2000]); # _Robert Israel_, Jul 23 2020

%o (PARI) is(n)=!(sigma(n+8)%(eulerphi(n)+8)) \\ _Charles R Greathouse IV_, Sep 25 2012

%Y Cf. A000010, A000203, A228353.

%K nonn

%O 1,1

%A _Robert G. Wilson v_

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

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Last modified April 19 12:14 EDT 2024. Contains 371792 sequences. (Running on oeis4.)