|
Search: id:A058764
|
|
|
| A058764 |
|
Smallest number x such that cototient(x) = 2^n. |
|
+0
5
|
|
| 2, 4, 6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072, 6144, 12288, 24576, 49152, 98304, 196608, 393216, 786432, 1572864, 3145728, 6291456, 12582912, 25165824, 50331648, 100663296
(list; graph; listen)
|
|
|
OFFSET
|
0,1
|
|
|
COMMENT
|
Since the cototient of 3*2^n is 2^(n+1), upper bounds are given by A007283(n-1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 13 2008]
|
|
FORMULA
|
a(n)=Min{x|A051953(x)=2^n}
|
|
EXAMPLE
|
a(5)=48, cototient(48)=48-Phi(48)=48-16=32. For n>2 a(n)=3.2^(n-1); largest solutions =2^(n+1); Prime factors of solutions: 2 and Mersenne-primes were found only.
|
|
CROSSREFS
|
Cf. A051953, A053579, A053650.
Cf. A042950. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 30 2009]
Sequence in context: A115387 A095849 A094783 this_sequence A087009 A168263 A162936
Adjacent sequences: A058761 A058762 A058763 this_sequence A058765 A058766 A058767
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Jan 02 2001
|
|
|
Search completed in 0.002 seconds
|
