OFFSET
1,2
LINKS
Robert G. Wilson v, 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.
MATHEMATICA
nn=10;
fam[n_]:=fam[n]=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[fam[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
nds=Length/@Array[fam[#]&, 2^nn];
Table[If[#=={}, 0, #[[1, 1]]]&[Position[nds, i]], {i, nn}]
CROSSREFS
All nonzero terms belong to A025487.
Includes all highly factorable numbers A033833.
The version without zeros is A045783.
The sorted version is A330972.
The strict version is A330974.
Positions of zeros are A330976.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 06 2020
EXTENSIONS
More terms from Jinyuan Wang, Jul 07 2021
STATUS
approved