The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
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!)
A200818 Numbers k such that (2^k - k)*2^k - 1 is prime. 7
2, 4, 5, 8, 77, 377, 4547, 8248, 27502 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
No more terms < 17000. - L. Joris Perrenet, Mar 17 2020
The generalization of this sequence is possible with the primes of the form (b^n +- k)*b^n +- 1.
LINKS
Henri Lifchitz, New forms of primes
EXAMPLE
4 is in the sequence because (2^4 - 4)*2^4 - 1 = 191 is prime.
MATHEMATICA
lst={}; Do[If[PrimeQ[(2^n - n)*2^n-1], AppendTo[lst, n]], {n, 10^3}]; lst
PROG
(PARI) is(n)=ispseudoprime((2^n-n)<<n-1) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Sequence in context: A013154 A013129 A104311 * A021980 A303496 A169624
KEYWORD
nonn,hard,more
AUTHOR
Michel Lagneau, Nov 23 2011
EXTENSIONS
a(8) from L. Joris Perrenet, Mar 17 2020
a(9) from Michael S. Branicky, Jul 14 2023
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 June 12 17:34 EDT 2024. Contains 373349 sequences. (Running on oeis4.)