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!)
A109602 Numbers n such that n!/(pi(n)!*2^n)+1 is prime. 0
1, 4, 5, 6, 7, 8, 9, 19, 20, 29, 31, 97, 113, 181, 286, 419, 485, 670, 1216 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Next term, if it exists, is > 3000. - Ray Chandler, Aug 04 2005
LINKS
MATHEMATICA
f[n_] := n!/Fold[Times, 1, Range[PrimePi[n]]]*2^n + 1; Do[ If[ PrimeQ[ f[n]], Print[n]], {n, 1000}]
CROSSREFS
Cf. A108894.
Sequence in context: A214419 A189481 A123977 * A084991 A356824 A099070
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jul 18 2005
EXTENSIONS
a(19)=1216 from Ray Chandler, Aug 04 2005
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 May 26 08:30 EDT 2024. Contains 372814 sequences. (Running on oeis4.)