login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A075539 Perfect powers n such that (n-5)/2 is prime. 0
9, 27, 2187, 19683, 300763, 1092727, 2048383, 6128487 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
9=3^2, 27=3^3, 2187=3^7, 19683=3^9, but 300763=67^3 - is there any rule?
MATHEMATICA
pp = Join[{1}, Select[ Range[10^7], Apply[GCD, Last[ Transpose[ FactorInteger[ # ]]]] > 1 & ]]; Select[pp, PrimeQ[(# - 5)/2] & ]
CROSSREFS
Sequence in context: A020254 A124396 A020281 * A225300 A053825 A328640
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Oct 11 2002
EXTENSIONS
Extended by Robert G. Wilson v, Oct 14 2002
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 02:46 EDT 2024. Contains 370952 sequences. (Running on oeis4.)