

A199295


Smallest prime factor of n^(n^n) + 1.


0




OFFSET

1,1


COMMENTS

Other known values: a(10)=307201, a(12)=10871635969, a(14)=977502209.  Arkadiusz Wesolowski, Jan 29 2012
a(8) > 10^20.  Max Alekseyev, Jul 31 2015
a(8) < 2^(2^24)+1 since 8^(8^8)+1 = (2^(2^24)+1) * (2^(2^25)2^(2^24)+1) and 2^(2^24)+1 (the 24th Fermat number) is known to be composite.  Sean A. Irvine, Jun 27 2017


LINKS

Table of n, a(n) for n=1..7.
G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 2424833


FORMULA

a(2*n1) = 2.


MATHEMATICA

lst = {}; r = 7; Do[k = 1; While[True, p = k*2^(n + 1) + 1; If[PrimeQ[p] && PowerMod[n, n^n, p] + 1 == p, Break[]]; k++]; AppendTo[lst, p], {n, 2, r, 2}]; lst = Flatten[Transpose@{Table[2, {Floor[r/2]}], lst}]; If[OddQ[r], AppendTo[lst, 2], lst] (* Arkadiusz Wesolowski, Jan 29 2012 *)


CROSSREFS

Sequence in context: A275588 A114560 A108883 * A162623 A165234 A155895
Adjacent sequences: A199292 A199293 A199294 * A199296 A199297 A199298


KEYWORD

hard,more,nonn


AUTHOR

Arkadiusz Wesolowski, Nov 04 2011


STATUS

approved



