




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^(2^51)1=2^311=2147483647.


MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[x=2^(2^p1)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



