A062698 - OEIS

%I #16 Dec 15 2017 17:35:13

%S 3,5,13,241,958003201,12804747411456001,

%T 20666295932772289859333302675046400000001,

%U 3102237506574764560448486032938606422126519440033972224000000000001,8549766568120051128596027506778799299380687576733627449344000000000001

%N Primes of form 2n! + 1.

%H Harry J. Smith, <a href="/A062698/b062698.txt">Table of n, a(n) for n=1,...,12</a>

%t lst={};Do[p=2*n!+1;If[PrimeQ[p],AppendTo[lst,p]],{n,0,5!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jan 28 2009 *)

%t Select[2*Range[200]!+1,PrimeQ] (* _Harvey P. Dale_, Oct 26 2013 *)

%o (PARI) for(n=1,55, if(isprime(2*n!+1),print(2*n!+1)))

%o (PARI) { n=0; f=1; for (m=1, 10^5, f*=m; if(isprime(a=2*f + 1), write("b062698.txt", n++, " ", a); if (n==12, break)) ) } \\ _Harry J. Smith_, Aug 09 2009

%K nonn

%O 1,1

%A _Jason Earls_, Jul 10 2001

%E One additional term from _Harvey P. Dale_, Oct 26 2013