login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

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