A249623 Conjectured least number k such that k^k - n^n is prime.

2, 3, 4, 15, 8, 7, 0, 347, 0, 11, 3682, 17, 0, 23, 0, 17, 26, 313, 30, 47, 400, 53, 1428, 0, 0, 77, 214, 195, 3820, 709, 270, 7653, 956, 9495, 0, 65, 396, 905, 0, 737, 0, 73, 0, 0, 1712, 0, 0, 0, 0, 0, 0, 167, 0, 383, 0, 0, 110, 0, 100, 0, 0, 3435, 2806, 0, 92, 1729, 84, 0, 0, 0, 122, 173, 3792, 0, 514, 0, 0, 163, 0, 101, 0, 195, 438, 277, 0, 369, 6392, 0, 294, 0, 0, 0, 122, 137, 6326, 0, 0, 0, 116

Offset

1,1

Comments

The zero entries are only conjectural.

a(7) > 15000 or 0. Other a(n) = 0 entries have been checked up to k = 10^4. - Jinyuan Wang, Aug 09 2020

Links

Table of n, a(n) for n=1..99.

Prog

(PARI) a(n)=k=1; while(k<7500, if(ispseudoprime(k^k-n^n), return(k)); k++)

Crossrefs

Cf. A249570.

Sequence in context: A085100 A337117 A204983 * A367742 A251637 A365436

Adjacent sequences: A249620 A249621 A249622 * A249624 A249625 A249626

Keyword

nonn,hard,more

Author

Derek Orr, Nov 02 2014

Extensions

a(32) and a(34) corrected by Jinyuan Wang, Aug 13 2020

Status

approved