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.

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

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.

Cf. A336296, A336297.

Sequence in context: A340640 A073045 A045967 * A232241 A163836 A175085

Adjacent sequences: A336442 A336443 A336444 * A336446 A336447 A336448

Keyword

nonn

Author

Michel Marcus, Jul 22 2020

Status

approved