A382370 Numbers k such that (k - 1)^(k + 1) - k is prime.

3, 4, 5, 7, 10, 11, 21, 46, 59, 839, 21920

Offset: 1

Author

Juri-Stepan Gerasimov, Mar 23 2025

Keywords

• nonn
• more

Comments

The corresponding primes are 13, 239, 4091, 1679609, 31381059599, 999999999989, 41943039999999999999999999979, ...

Crossrefs

Cf. A238378, A240532.

Programs

Magma

[k: k in [2..500] | IsPrime((k-1)^(k+1)-k)];

Mathematica

Select[Range[1000], PrimeQ[(#-1)^(#+1)-#] &] (* Stefano Spezia, Mar 30 2025 *)

Extensions

a(11) from Michael S. Branicky, Mar 25 2025