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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
4, 9, 25, 30, 49, 70, 84, 105, 121, 169, 231, 234, 260, 286, 289, 361, 456, 529, 532, 627, 646, 805, 841, 897, 961, 1116, 1364, 1369, 1581, 1665, 1681, 1798, 1849, 1924, 2064, 2150, 2209, 2632, 2809, 2967, 3055, 3339, 3481, 3526, 3721, 4489, 4543, 4824, 5025, 5041 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
All squares of primes (A001248) are terms.
LINKS
Michel Marcus, Table of n, a(n) for n = 1..1049 (terms up to 10^7)
EXAMPLE
4 is a term since sopf(4)=2 and 4/2 = 2 is a prime.
30 is a term since sopf(30)=10 and 30/10 = 3 is a prime.
PROG
(PARI) sopf(n)=vecsum(factor(n)[, 1]); \\ A008472
isokp(k) = my(q=k/sopf(k)); (denominator(q)==1) && isprime(q);
CROSSREFS
Cf. A008472 (sopf).
Subsequence of A071139.
A001248 is a subsequence.
Sequence in context: A340640 A073045 A045967 * A232241 A163836 A175085
KEYWORD
nonn
AUTHOR
Michel Marcus, Jul 22 2020
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)