A063080 Numbers k such that k/d(k) is prime, where d(k) is the number of divisors of k.

8, 9, 12, 18, 24, 40, 56, 60, 84, 88, 104, 132, 136, 152, 156, 184, 204, 228, 232, 248, 276, 296, 328, 344, 348, 372, 376, 424, 444, 472, 488, 492, 516, 536, 564, 568, 584, 632, 636, 664, 708, 712, 732, 776, 804, 808, 824, 852, 856, 872, 876, 904, 948, 996

Offset: 1

Author

Jason Earls, Aug 05 2001

Keywords

• easy
• nonn

Comments

If p is an odd prime, then 8*p is a term. - Amiram Eldar, Apr 17 2024

Examples

			k = 18: 18/d(18) = 3 a prime.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)

Crossrefs

Cf. A000005, A039819, A036762, A051278, A051279, A051280, A036763, A033950.

Programs

Mathematica

Select[Range[1000],PrimeQ[#/DivisorSigma[0,#]]&] (* Harvey P. Dale, Sep 01 2014 *)

PARI

ok(m)={my(d=numdiv(m)); m%d==0 && isprime(m/d)}