A341044 - OEIS

%I #10 Feb 04 2021 05:42:12

%S 8,9,10,14,15,21,22,25,26,33,34,39,42,46,57,62,65,66,69,72,74,76,80,

%T 82,87,91,92,93,94,95,100,106,111,116,119,121,122,129,133,134,145,146,

%U 159,162,166,172,176,177,183,184,190,194,202,203,206,208,213,214,215,219,232,236,237,238,240,243

%N Numbers k such that A318996(k) is prime.

%C Contains 2*p for p in A023201 and 3*p for p in A023203.

%H Robert Israel, <a href="/A341044/b341044.txt">Table of n, a(n) for n = 1..10000</a>

%e a(3) = 10 is a term because A318996(10) = 11 is prime.

%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 -> isprime(f(t)), [$1..1000]);

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

%o isok(k) = isprime(f(k)); \\ _Michel Marcus_, Feb 04 2021

%Y Cf. A023201, A023203, A318996.

%K nonn

%O 1,1

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