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A336445 Integers m such that m/sopf(m) is a prime number where sopf(m) is A008472(m), the sum of the distinct primes dividing m. 2

%I #15 Jul 24 2020 01:52:49

%S 4,9,25,30,49,70,84,105,121,169,231,234,260,286,289,361,456,529,532,

%T 627,646,805,841,897,961,1116,1364,1369,1581,1665,1681,1798,1849,1924,

%U 2064,2150,2209,2632,2809,2967,3055,3339,3481,3526,3721,4489,4543,4824,5025,5041

%N Integers m such that m/sopf(m) is a prime number where sopf(m) is A008472(m), the sum of the distinct primes dividing m.

%C All squares of primes (A001248) are terms.

%H Michel Marcus, <a href="/A336445/b336445.txt">Table of n, a(n) for n = 1..1049</a> (terms up to 10^7)

%e 4 is a term since sopf(4)=2 and 4/2 = 2 is a prime.

%e 30 is a term since sopf(30)=10 and 30/10 = 3 is a prime.

%o (PARI) sopf(n)=vecsum(factor(n)[, 1]); \\ A008472

%o isokp(k) = my(q=k/sopf(k)); (denominator(q)==1) && isprime(q);

%Y Cf. A008472 (sopf).

%Y Subsequence of A071139.

%Y A001248 is a subsequence.

%Y Cf. A336296, A336297.

%K nonn

%O 1,1

%A _Michel Marcus_, Jul 22 2020

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Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)