A302088 - OEIS

A302088

Numbers k such that 5*k^k + 4 is prime.

3, 5, 9, 183, 561

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OFFSET

1,1

COMMENTS

a(6), if it exists, is greater than 5000. - Vaclav Kotesovec, Apr 01 2018

a(6), if it exists, is greater than 20000. - Michael S. Branicky, Sep 02 2024

LINKS

MATHEMATICA

Select[Range[1, 1000], PrimeQ[5*#^# + 4] &] (* Vaclav Kotesovec, Apr 01 2018 *)

PROG

(PARI) for(n=0, 500, if(isprime(5*n^n+4), print1(n", ")))

(PARI) lista(nn) = forstep(n=1, nn, 2, if(ispseudoprime(5*n^n+4), print1(n, ", "))); \\ Altug Alkan, Apr 01 2018

CROSSREFS

Numbers k such that b*k^k + b - 1 is prime: A110932 (b=2), A160360 (b=3), A301520 (b=4), this sequence (b=5), A302090 (b=6).

KEYWORD

nonn,more,hard

AUTHOR

EXTENSIONS

a(5) from Vaclav Kotesovec, Apr 01 2018

STATUS

approved