|
|
A322075
|
|
Number of factorizations of n into nonprime squarefree numbers > 1.
|
|
2
|
|
|
1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,210
|
|
COMMENTS
|
First term greater than 1 is a(210) = 4.
|
|
LINKS
|
|
|
EXAMPLE
|
The a(420) = 3 factorizations: (6*70), (10*42), (14*30).
|
|
MATHEMATICA
|
sqnopfacs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[sqnopfacs[n/d], Min@@#>=d&]], {d, Select[Rest[Divisors[n]], !PrimeQ[#]&&SquareFreeQ[#]&]}]]
Table[Length[sqnopfacs[n]], {n, 100}]
|
|
CROSSREFS
|
Cf. A000469, A001055, A001221, A001222, A005117, A007716, A318871, A318953, A320655, A320656, A320658, A320659.
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|