

A058912


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


4




OFFSET

1,1


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


LINKS

Table of n, a(n) for n=1..8.


EXAMPLE

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


MATHEMATICA

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


PROG

(PARI) is(n)=ispseudoprime(n^n+n1) \\ Charles R Greathouse IV, Feb 20 2017


CROSSREFS

Cf. A058911 (k^k + k + 1 is prime).
Sequence in context: A140555 A196446 A265799 * A040145 A142955 A213896
Adjacent sequences: A058909 A058910 A058911 * A058913 A058914 A058915


KEYWORD

nonn,more,hard


AUTHOR

Felice Russo, Jan 10 2001


EXTENSIONS

a(6) from Farideh Firoozbakht, Oct 18 2006
a(7)a(8) from Hugo Pfoertner, Mar 02 2020


STATUS

approved



