

A100361


Numbers n such that 2^nn+1 is prime.


7



0, 1, 2, 4, 6, 16, 18, 54, 58, 100, 120, 504, 1302, 3234, 14748, 16102, 22782, 34656, 64764, 70866, 194940, 274074, 313344, 331416, 354640
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OFFSET

1,3


COMMENTS

a(21) > 150000.  Giovanni Resta, Mar 18 2014
a(26) > 5*10^5.  Robert Price, Oct 13 2014


LINKS

Table of n, a(n) for n=1..25.


MAPLE

A100361:=n>`if`(isprime(2^nn+1), n, NULL): seq(A100361(n), n=0..10^3); # Wesley Ivan Hurt, Oct 13 2014


MATHEMATICA

{ta={{0}}, tb={{0}}}; Do[g=n; s=2^nn+1; If[PrimeQ[s], Print[n]; ta=Append[ta, n]; tb=Append[tb, s]], {n, 1, 10000}]; {ta, tb, g}


PROG

(PARI) is(n)=ispseudoprime(2^nn+1) \\ Charles R Greathouse IV, Feb 20 2017


CROSSREFS

Cf. A001580, A069539, A052007, A048744, A100357A100359, A061421.
Sequence in context: A096173 A287681 A114874 * A259939 A069654 A000068
Adjacent sequences: A100358 A100359 A100360 * A100362 A100363 A100364


KEYWORD

hard,more,nonn


AUTHOR

Labos Elemer, Nov 19 2004


EXTENSIONS

a(15)a(20) from Giovanni Resta, Mar 18 2014
a(21)a(25) from Robert Price, Oct 13 2014


STATUS

approved



