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!)
A225392 Numbers b such that b^(2^n) + 2 is prime for n from 0 to 4. 0
22155, 1864149, 2760681, 6222765, 22687797, 25631319, 29309589, 33333069, 36490905, 56310891, 60212889, 74097849, 76008207, 80864685, 84214395, 132006225, 132621171, 137362521, 138993381, 152223885, 154185525, 175950081, 188261481, 188677335, 194279955 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Generalized Fermat numbers of the form b^(2^n) + k with k = 2 here.
For b = 2760681, b^(2^n) + 2 is prime for n from 0 to 5
LINKS
PROG
(PARI) k=2; forstep(b=1, 5*10^7, [4, 2, 2, 2], i=0; for(n=0, 4, m=b^2^n+k; if(isprime(m), i++; if(i>4, print([b, m, n, i])))))
CROSSREFS
Sequence in context: A043590 A043815 A157622 * A225998 A209396 A210295
KEYWORD
nonn
AUTHOR
Robin Garcia, May 06 2013
EXTENSIONS
a(10)-a(25) from Giovanni Resta, May 06 2013
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 16 07:19 EDT 2024. Contains 373423 sequences. (Running on oeis4.)