|
Search: id:A078541
|
|
|
| A078541 |
|
Refactorable numbers x, such that quotient x/A00005[x] equals a power of 2. |
|
+0
1
|
|
| 1, 2, 8, 12, 36, 80, 96, 128, 288, 448, 2560, 6144, 11264, 18432, 32768, 53248, 57344, 245760, 737280, 1114112, 2621440, 4980736, 22020096, 23068672, 25165824, 66060288, 75497472, 96468992
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
FORMULA
|
a[n]/tau(a[n])=2^s with some s, tau()=A000005()
|
|
EXAMPLE
|
a(6)=80: tau[80]=20, quotient=80/20=4=2.2; certain powers of 2 do not appear as quotient, like 64, 1024, 16384.
|
|
MATHEMATICA
|
Do[s=n/DivisorSigma[0, n]; If[IntegerQ[Log[2, s]], Print[{n, s, n/s}]], {n, 1, 1000000000}]
|
|
CROSSREFS
|
Cf. A000005, A033950, A036763, A051278, A051279, A051280.
Sequence in context: A037197 A125712 A062290 this_sequence A135443 A104039 A083546
Adjacent sequences: A078538 A078539 A078540 this_sequence A078542 A078543 A078544
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Dec 04 2002
|
|
|
Search completed in 0.002 seconds
|
