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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A077586 2^(2^p-1)-1. 3
7, 127, 2147483647, 170141183460469231731687303715884105727 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

First four terms are primes. Fifth (1.61585...*10^616), sixth (5.45374...*10^2465), seventh (2.007...*10^39456) and eighth (1.298...*10^157826) are not primes.

LINKS

Table of n, a(n) for n=1..4.

Eric Weisstein's World of Mathematics, Double Mersenne Number

FORMULA

a(n) =A077585(A000040(n)) =A000225(A001348(n))

EXAMPLE

a(3)=2^(2^5-1)-1=2^31-1=2147483647.

MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[x=2^(2^p-1)-1], Print[x]; AppendTo[lst, n]], {n, 10^9}]; lst [From Vladimir Joseph Stephan Orlovsky, Aug 21 2008]

CROSSREFS

Sequence in context: A077585 A134722 A053713 * A002614 A187237 A095885

Adjacent sequences:  A077583 A077584 A077585 * A077587 A077588 A077589

KEYWORD

nonn

AUTHOR

Henry Bottomley, Nov 07 2002

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 September 16 15:27 EDT 2014. Contains 246817 sequences.