|
|
A340689
|
|
Numbers with a factorization of length 2^k into factors > 1, where k is the greatest factor.
|
|
5
|
|
|
1, 16, 384, 576, 864, 1296, 1944, 2916, 4374, 6561, 131072, 196608, 262144, 294912, 393216, 442368, 524288, 589824, 663552, 786432, 884736, 995328, 1048576, 1179648, 1327104, 1492992, 1572864, 1769472, 1990656, 2097152, 2239488, 2359296, 2654208, 2985984, 3145728
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
The initial terms and a valid factorization of each are:
1 =
16 = 2*2*2*2
384 = 2*2*2*2*2*2*2*3
576 = 2*2*2*2*2*2*3*3
864 = 2*2*2*2*2*3*3*3
1296 = 2*2*2*2*3*3*3*3
1944 = 2*2*2*3*3*3*3*3
2916 = 2*2*3*3*3*3*3*3
4374 = 2*3*3*3*3*3*3*3
6561 = 3*3*3*3*3*3*3*3
131072 = 2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*4
196608 = 2*2*2*2*2*2*2*2*2*2*2*2*2*2*3*4
262144 = 2*2*2*2*2*2*2*2*2*2*2*2*2*2*4*4
294912 = 2*2*2*2*2*2*2*2*2*2*2*2*2*3*3*4
|
|
MATHEMATICA
|
facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Select[Range[1000], Select[facs[#], Length[#]==2^Max@@#&]!={}&]
|
|
CROSSREFS
|
Partitions of the prescribed type are counted by A340611.
A047993 counts balanced partitions.
A316439 counts factorizations by product and length.
A340596 counts co-balanced factorizations.
A340597 lists numbers with an alt-balanced factorization.
A340653 counts balanced factorizations.
Cf. A106529, A117409, A200750, A325134, A340386, A340387, A340599, A340607, A340654, A340655, A340656, A340657.
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|