login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A195166 Numbers expressible as 2^a-2^b, with 0 <= b< a, such that n^a-n^b is divisible by 2^a-2^b for all n. 0
1, 2, 6, 12, 30, 24, 60, 120, 252, 240, 504, 16380, 32760, 65520 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

1     = 2^1  - 2^0. (n^1  - n^0)/1     : A000027

2     = 2^2  - 2^1. (n^2  - n^1)/2     : A000217

6     = 2^3  - 2^1. (n^3  - n^1)/6     : A000292

12    = 2^4  - 2^2. (n^4  - n^2)/12    : A002415

30    = 2^5  - 2^1. (n^5  - n^1)/30    : A033455

24    = 2^5  - 2^3. (n^5  - n^3)/24    : A006414

60    = 2^6  - 2^2. (n^6  - n^2)/60    : A213547

120   = 2^7  - 2^3. (n^7  - n^3)/120   : A114239

252   = 2^8  - 2^2. (n^8  - n^2)/252   :

240   = 2^8  - 2^4. (n^8  - n^4)/240   : A078876

504   = 2^9  - 2^3. (n^9  - n^3)/504   :

16380 = 2^14 - 2^2. (n^14 - n^2)/16380 :

32760 = 2^15 - 2^3. (n^15 - n^3)/32760 :

65520 = 2^16 - 2^4. (n^16 - n^4)/65520 :

LINKS

Table of n, a(n) for n=1..14.

Qi Sun and Ming Zhi Zhang, Pairs where 2^a-2^b divides n^a-n^b for all n, Proc. Amer. Math. Soc. 93 (1985), 218-220

CROSSREFS

Sequence in context: A093387 A324408 A229487 * A225646 A225627 A237704

Adjacent sequences:  A195163 A195164 A195165 * A195167 A195168 A195169

KEYWORD

nonn,fini,full

AUTHOR

Michel Marcus, Dec 21 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 17 22:17 EDT 2019. Contains 324200 sequences. (Running on oeis4.)