OFFSET
2,3
COMMENTS
a(1)=infinity is not an integer so is necessarily omitted from the data.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 2..1000
EXAMPLE
The a(64)=17 ways to write 64 as a power of a product:
(2*2*2*2*2*2)^1 (2*2*2)^2 (2*2)^3 (2)^6
(2*2*2*2*4)^1 (2*4)^2 (4)^3
(2*2*2*8)^1 (8)^2
(2*2*4*4)^1
(2*2*16)^1
(2*4*8)^1
(2*32)^1
(4*4*4)^1
(4*16)^1
(8*8)^1
(64)^1.
MATHEMATICA
nn=85;
postfacs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[postfacs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Table[DivisorSum[GCD@@FactorInteger[n][[All, 2]], Length[postfacs[n^(1/#)]]&], {n, 2, nn}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 30 2017
STATUS
approved