login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A050523 Primes of form 7*2^n-1. 1
13, 223, 3583, 917503, 14680063, 3758096383, 246290604621823, 1340933598257652751063553648756520535666396731910651903 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..8.

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

MATHEMATICA

Select[Table[7*2^n-1, {n, 0, 200}] , PrimeQ] (* Jean-Fran├žois Alcover, Mar 20 2011 *)

CROSSREFS

See A001771 for more terms.

Cf. A158795 [Vincenzo Librandi, Mar 28 2009 ]

Sequence in context: A178559 A068120 A237602 * A160196 A218588 A158518

Adjacent sequences:  A050520 A050521 A050522 * A050524 A050525 A050526

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Dec 29 1999

EXTENSIONS

13 inserted by R. J. Mathar, Apr 01 2009

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 22 16:29 EST 2020. Contains 331152 sequences. (Running on oeis4.)