A100840 Primes of the form k^k + 4.

5, 31, 823547, 17343773367030267519903781288812032158308062539012091953077767198995511

Offset: 1

Author

Cino Hilliard, Jan 07 2005

Keywords

• hard
• nonn

Comments

From Daniel Starodubtsev, Aug 03 2019: (Start)

a(5) = 2569^2569 + 4 (8760 digits long).

a(6) > 15000^15000 + 4. (End)

Crossrefs

Cf. A100837 (corresponding k).

Programs

Mathematica

lst={};Do[p=n^n+4;If[PrimeQ[p],AppendTo[lst,p]],{n,5!}];lst (* Vladimir Joseph Stephan Orlovsky, Nov 01 2009 *)
Select[Table[n^n+4,{n,50}],PrimeQ] (* Harvey P. Dale, Oct 09 2020 *)

PARI

f1(n) = for(x=1,n,y=x^x+4;if(ispseudoprime(y),print1(y", ")))