login
This site is supported by donations to The OEIS Foundation.

 

Logo

Many excellent designs for a new banner were submitted. We will use the best of them in rotation.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A051915 Numbers n such that 2*n! + 1 is a prime. 9
0, 1, 2, 3, 5, 12, 18, 35, 51, 53, 78, 209, 396, 4166 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Used PrimeForm to prove primality for n = 4166 (classical N-1 test) - David Radcliffe, May 28 2007

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

n=5 is here because 2*5!+1=241 is a prime.

MATHEMATICA

Select[Range[0, 400], PrimeQ[2*#! + 1] &] (* Vladimir Joseph Stephan Orlovsky, Feb 13 2012 *)

CROSSREFS

Cf. A051888.

Sequence in context: A002139 A140489 A193776 * A064688 A089891 A004689

Adjacent sequences:  A051912 A051913 A051914 * A051916 A051917 A051918

KEYWORD

nonn

AUTHOR

Labos Elemer, Dec 18 1999

EXTENSIONS

4166 from David Radcliffe, May 28 2007

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified April 21 06:23 EDT 2014. Contains 240824 sequences.