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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
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}]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 25 2018
STATUS
approved