A300976 Numbers k such that k^k - 5 is a prime.

4, 104, 124, 728

Offset

1,1

Comments

728^728 - 5 is a probable prime.

Next term, if it exists, is greater than 5000. - Vaclav Kotesovec, Mar 25 2018

Next term, if it exists, is greater than 31000. - Robert Price, Mar 26 2018

Links

Table of n, a(n) for n=1..4.

Mathematica

Select[Range[1000], PrimeQ[#^# - 5] &] (* Vaclav Kotesovec, Mar 25 2018 *)

Prog

(PARI) isok(k) = ispseudoprime(k^k - 5); \\ Altug Alkan, Mar 17 2018

Crossrefs

Numbers k such that k^k + b is a prime: A300981 (b=-10), this sequence (b=-5), A100408 (b=-2), A100407 (b=2), A166852 (b=3), A100837 (b=4), A100838 (b=7), A300292 (b=9), A100839 (b=10), A173974 (b=43).

Sequence in context: A353312 A024056 A353311 * A102439 A331456 A211150

Adjacent sequences: A300973 A300974 A300975 * A300977 A300978 A300979

Keyword

nonn,hard,more

Author

Seiichi Manyama, Mar 17 2018

Status

approved