A054463 Numbers k such that (k+1)^k - k^(k-1) is prime.

2, 5, 6, 9, 24, 595

Offset: 1

Author

Cino Hilliard, Aug 30 2003

Keywords

• nonn
• more

Comments

a(7) > 3000, if it exists. - Amiram Eldar, Jun 28 2024

a(7) > 20000, if it exists. - Michael S. Branicky, Jan 07 2025

Programs

Mathematica

Select[Range[1000], PrimeQ[(# + 1)^# - #^(# - 1)] &] (* Vincenzo Librandi, Sep 27 2012 *)

PARI

xp1toxp1(n)= { my(y); forstep(x=2,n,1, y=(x+1)^x - x^(x-1); if(ispseudoprime(y), print1(x, ", "))); }

Extensions

a(6) from Vincenzo Librandi, Sep 27 2012