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A063080
Numbers k such that k/d(k) is prime, where d(k) is the number of divisors of k.
1
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
1,1
COMMENTS
If p is an odd prime, then 8*p is a term. - Amiram Eldar, Apr 17 2024
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)
EXAMPLE
k = 18: 18/d(18) = 3 a prime.
MATHEMATICA
Select[Range[1000], PrimeQ[#/DivisorSigma[0, #]]&] (* Harvey P. Dale, Sep 01 2014 *)
PROG
(PARI) ok(m)={my(d=numdiv(m)); m%d==0 && isprime(m/d)}
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Aug 05 2001
STATUS
approved