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Numbers k such that k^k + k + 5 is prime.
2

%I #18 Jun 30 2024 06:38:07

%S 1,2,37,451,1699,2131,12612

%N Numbers k such that k^k + k + 5 is prime.

%C Here we interpret 0^0 as 1.

%C a(7) > 10^4. [From _D. S. McNeil_, Mar 14 2009]

%C a(8) > 2*10^4. - _Michael S. Branicky_, Jun 30 2024

%o (PARI) f2(n) = for(x=0,n,y=x^x+x+5;if(ispseudoprime(y),print1(x", ")))

%Y Cf. A100848, A100850.

%K hard,more,nonn

%O 1,2

%A _Cino Hilliard_, Jan 07 2005

%E a(5)-a(6) from _D. S. McNeil_, Mar 14 2009

%E a(7) from _Michael S. Branicky_, Jun 29 2024