|
|
A340851
|
|
Number of factorizations of n such that every factor is a divisor of the number of factors.
|
|
8
|
|
|
1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,64
|
|
COMMENTS
|
Also factorizations whose number of factors is divisible by their least common multiple.
|
|
LINKS
|
|
|
EXAMPLE
|
The a(n) factorizations for n = 8192, 46656, 73728:
2*2*2*2*2*4*8*8 6*6*6*6*6*6 2*2*2*2*2*2*2*2*2*4*6*6
2*2*2*2*4*4*4*8 2*2*2*2*2*2*3*3*3*3*3*3 2*2*2*2*2*2*2*2*3*4*4*6
2*2*2*4*4*4*4*4 2*2*2*2*2*2*2*3*3*4*4*4
2*2*2*2*2*2*2*2*2*2*2*4 2*2*2*2*2*2*2*2*2*2*6*12
2*2*2*2*2*2*2*2*2*3*4*12
|
|
MATHEMATICA
|
facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Table[Length[Select[facs[n], And@@IntegerQ/@(Length[#]/#)&]], {n, 100}]
|
|
CROSSREFS
|
The version for partitions is A340693, with reciprocal version A143773.
Positions of nonzero terms are A340852.
A320911 can be factored into squarefree semiprimes.
A340597 have an alt-balanced factorization.
- Factorizations -
A316439 counts factorizations by product and length.
A339846 counts factorizations of even length.
A339890 counts factorizations of odd length.
A340101 counts factorizations into odd factors, odd-length case A340102.
A340653 counts balanced factorizations.
A340785 counts factorizations into even numbers, even-length case A340786.
Cf. A067538, A074761, A168659, A301987, A327517, A340596, A340599, A340654, A340655, A340827, A340830.
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|