A062698 Primes of form 2*k! + 1.

3, 5, 13, 241, 958003201, 12804747411456001, 20666295932772289859333302675046400000001, 3102237506574764560448486032938606422126519440033972224000000000001, 8549766568120051128596027506778799299380687576733627449344000000000001

Offset: 1

Author

Jason Earls, Jul 10 2001

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n=1,...,12

Crossrefs

Cf. A051915, A052898.

Programs

Mathematica

lst={};Do[p=2*n!+1;If[PrimeQ[p],AppendTo[lst,p]],{n,0,5!}];lst (* Vladimir Joseph Stephan Orlovsky, Jan 28 2009 *)
Select[2*Range[200]!+1,PrimeQ] (* Harvey P. Dale, Oct 26 2013 *)

PARI

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

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

Formula

a(n) = A052898(A051915(n+1)). - Elmo R. Oliveira, Apr 16 2025

Extensions

One additional term from Harvey P. Dale, Oct 26 2013