A341045 - OEIS

%I #15 Feb 04 2021 07:26:21

%S 1,4,6,28,45,120,496,672,6048,8128,14421,30240,32760,523776,2178540,

%T 23569920,26409026,29270772,30685402,33550336,45532800

%N Numbers k such that k divides A318996(k).

%e a(2) = 4 is a term because A318996(4) = 4 is divisible by 4.

%e a(3) = 6 is a term because A318996(6) = 0 is divisible by 6.

%p f:= proc(n) local s,D,t;

%p   D:= numtheory:-divisors(n);

%p   s:= convert(D,`+`);

%p   add(s mod t, t=D)

%p end proc:

%p select(t -> f(t) mod t = 0, [$1..20000]);

%o (PARI) f(n) = my(sn = sigma(n)); sumdiv(n, d, sn % d); \\ A318996

%o isok(k) = !(f(k) % k); \\ _Michel Marcus_, Feb 03 2021

%Y Contains A007691.

%Y Cf. A318996.

%K nonn,more

%O 1,2

%A _J. M. Bergot_ and _Robert Israel_, Feb 03 2021