

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.
Results were computed using the PrimeFormGW (PFGW) primalitytesting program.  Hugo Pfoertner, Nov 14 2019


LINKS

Table of n, a(n) for n=1..32.


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



