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A058911
Numbers k such that k^k + k + 1 is prime.
3
0, 1, 2, 3, 6, 9, 462
OFFSET
1,3
COMMENTS
There is no further term up to 10000. - Farideh Firoozbakht, Nov 11 2006
If it exists, a(8) > 32100. - Dmitry Petukhov, Sep 14 2021
EXAMPLE
a(2) = 2 because 2^2 + 2 + 1 = 7.
MATHEMATICA
Do[ If[ PrimeQ[ n^n + n + 1], Print[n]], {n, 1, 700} ]
Join[{0}, Select[Range[470], PrimeQ[#^#+#+1]&]] (* Harvey P. Dale, Dec 11 2022 *)
PROG
(PARI) f2(n, k) = for(x=1, n, y=x^x+x+k; if(ispseudoprime(y), print1(x", "))) \\ Cino Hilliard, Jan 07 2005
(PFGW) ABC2 $a^$a + $a + 1
a: from 0 to 1000 // Jinyuan Wang, Mar 01 2020
CROSSREFS
Cf. A058912 (k^k + k - 1 is prime), A161471 (corresponding primes).
Sequence in context: A071714 A077753 A353122 * A249247 A276956 A276946
KEYWORD
nonn,hard,more
AUTHOR
Felice Russo, Jan 10 2001
STATUS
approved