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 A058912 Numbers k such that k^k + k - 1 is prime. 4

%I

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

%N Numbers k such that k^k + k - 1 is prime.

%C Except for the first term all terms are of the form 3k or 3k+1. - _Farideh Firoozbakht_, Oct 18 2006

%C Corresponding values of primes are in A187605. - _Jaroslav Krizek_, Nov 14 2013

%C If it exists, a(9) > 16100. - _Hugo Pfoertner_, Mar 02 2020

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

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

%o (PARI) is(n)=ispseudoprime(n^n+n-1) \\ _Charles R Greathouse IV_, Feb 20 2017

%Y Cf. A058911 (k^k + k + 1 is prime).

%K nonn,more,hard

%O 1,1

%A _Felice Russo_, Jan 10 2001

%E a(6) from _Farideh Firoozbakht_, Oct 18 2006

%E a(7)-a(8) from _Hugo Pfoertner_, Mar 02 2020

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Last modified December 4 21:30 EST 2020. Contains 338939 sequences. (Running on oeis4.)