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!)
A032361 Numbers k such that 23*2^k+1 is prime. 1
1, 9, 13, 29, 41, 49, 69, 73, 341, 381, 389, 649, 1961, 3929, 977541, 1399841, 1448461, 2425641, 4300741 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Ray Ballinger, Proth Search Page
Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
MATHEMATICA
Select[Range[4000], PrimeQ[23 2^# + 1] &] (* Vincenzo Librandi, Sep 26 2012 *)
PROG
(PARI) is(n)=ispseudoprime(23*2^n+1) \\ Charles R Greathouse IV, Jun 06 2017
CROSSREFS
Sequence in context: A175532 A098074 A366997 * A031196 A151725 A146864
KEYWORD
nonn,hard
AUTHOR
EXTENSIONS
Added more terms (from http://www.prothsearch.com/riesel1.html), Joerg Arndt, Apr 07 2013
a(19) from Jeppe Stig Nielsen, Oct 11 2019
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 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)