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A068975 Composite k such that (k+1) * Sum_{d|k} d/sigma(d) is an integer. 0

%I #9 Mar 26 2024 21:45:00

%S 39,215,623,1023,1343,1455,2303,2431,2519,9503,13039,13055,13319,

%T 23759,24479,29183,44863,58463,58559,82583,85359,87295,99863,123463,

%U 136079,144143,147455,154623,196095,273023,283727,294839,390239,435455,450743

%N Composite k such that (k+1) * Sum_{d|k} d/sigma(d) is an integer.

%C If k is prime, trivially (k+1) * Sum_{d|k} d/sigma(d) = 2k+1 is an integer.

%K easy,nonn

%O 1,1

%A _Benoit Cloitre_, Apr 06 2002

%E More terms from Lambert Klasen (Lambert.Klasen(AT)gmx.net), Jan 03 2005

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Last modified June 16 19:52 EDT 2024. Contains 373432 sequences. (Running on oeis4.)