A058912 Numbers k such that k^k + k - 1 is prime.

2, 3, 19, 30, 535, 1551, 7069, 8508

Offset: 1

Author

Felice Russo, Jan 10 2001

Keywords

• nonn
• more
• hard

Comments

Except for the first term all terms are of the form 3k or 3k+1. - Farideh Firoozbakht, Oct 18 2006

Corresponding values of primes are in A187605. - Jaroslav Krizek, Nov 14 2013

If it exists, a(9) > 16100. - Hugo Pfoertner, Mar 02 2020

If it exists, a(9) > 31100. - Dmitry Petukhov, Sep 14 2021

Examples

			3 is a term because 3^3 + 3 - 1 = 29.
		

Crossrefs

Cf. A058911 (k^k + k + 1 is prime), A187605 (corresponding primes).

Programs

Mathematica

Do[ If[ PrimeQ[ n^n + n - 1], Print[n]], {n, 1, 750} ]

PARI

is(n)=ispseudoprime(n^n+n-1) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

a(6) from Farideh Firoozbakht, Oct 18 2006

a(7)-a(8) from Hugo Pfoertner, Mar 02 2020