OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
R. E. Canfield, P. Erdős and C. Pomerance, On a Problem of Oppenheim concerning "Factorisatio Numerorum", J. Number Theory 17 (1983), 1-28.
EXAMPLE
Factorizations of selected terms:
(4) (8) (16) (24) (60) (96)
(2*2) (2*4) (2*8) (3*8) (2*30) (2*48)
(2*2*2) (4*4) (4*6) (3*20) (3*32)
(2*2*4) (2*12) (4*15) (4*24)
(2*2*2*2) (2*2*6) (5*12) (6*16)
(2*3*4) (6*10) (8*12)
(2*2*2*3) (2*5*6) (2*6*8)
(3*4*5) (3*4*8)
(2*2*15) (4*4*6)
(2*3*10) (2*2*24)
(2*2*3*5) (2*3*16)
(2*4*12)
(2*2*3*8)
(2*2*4*6)
(2*3*4*4)
(2*2*2*12)
(2*2*2*2*6)
(2*2*2*3*4)
(2*2*2*2*2*3)
MATHEMATICA
facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Select[Range[100], PrimeQ[Length[facs[#]]]&]
CROSSREFS
Numbers whose number of strict integer partitions is prime are A035359.
Numbers whose number of integer partitions is prime are A046063.
Numbers whose number of set partitions is prime are A051130.
Numbers whose number of factorizations is a power of 2 are A330977.
The least number with prime(n) factorizations is A330992(n).
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 07 2020
STATUS
approved