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 A058912 Numbers k such that k^k + k - 1 is prime. 6
 2, 3, 19, 30, 535, 1551, 7069, 8508 (list; graph; refs; listen; history; text; internal format)
 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 If it exists, a(9) > 31100. - Dmitry Petukhov, Sep 14 2021 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+n-1) \\ Charles R Greathouse IV, Feb 20 2017 CROSSREFS Cf. A058911 (k^k + k + 1 is prime), A187605 (corresponding primes). Sequence in context: A196446 A341599 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

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Last modified September 22 07:13 EDT 2023. Contains 365519 sequences. (Running on oeis4.)