

A095991


Numbers n such that f(k) * 2^n  1 is prime, where f(j) = A070826(j) and k is the number of decimal digits of 2^n.


0



2, 3, 4, 6, 14, 17, 18, 23, 33, 43, 45, 53, 60, 70, 114, 141, 162, 178, 387, 657, 787, 951, 1517, 1882, 1999, 2423, 2722, 3635, 3636, 3893, 5021, 5631
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OFFSET

1,1


COMMENTS

a(1) through a(32) have been proved to be prime with WinPFGW. a(32) has 7901 digits. No more terms up to 7300.


LINKS

Table of n, a(n) for n=1..32.
PFGW, Discussion group for the PrimeForm program.


EXAMPLE

a(5)=14 because 1155 * 2^14  1 = 18923519, a prime.


MATHEMATICA

Do[ If[ PrimeQ[ Product[ Prime[i], {i, Floor[ n / Log[2, 10] + 1]}] * 2^(n  1)  1], Print[n]], {n, 7300}] (* Robert G. Wilson v, Jul 23 2004 *)


CROSSREFS

Sequence in context: A038767 A188715 A174046 * A293714 A049911 A056712
Adjacent sequences: A095988 A095989 A095990 * A095992 A095993 A095994


KEYWORD

more,nonn,base


AUTHOR

Jason Earls, Jul 18 2004


EXTENSIONS

Edited by Robert G. Wilson v, Jul 23 2004


STATUS

approved



