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 A006033 Numbers n such that (15^n - 1)/14 is prime. (Formerly M3150) 13
 3, 43, 73, 487, 2579, 8741, 37441, 89009, 505117, 639833 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 8741 and 37441 are only probable primes. - Julien Peter Benney (jpbenney(AT)ftml.net), Apr 27 2007 REFERENCES Paulo Ribenboim, "The Book Of Prime Number Records"; published 1989 by Springer-Verlag; pages 350-354. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS P. Bourdelais, A Generalized Repunit Conjecture Harvey Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930. H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930. [Annotated scanned copy] Henri Lifchitz, Mersenne and Fermat primes field Index to primes in various ranges, form ((k+1)^n-1)/k EXAMPLE (15^3 - 1)/14 = 241, which is prime. MATHEMATICA lst={}; Do[If[PrimeQ[(15^n-1)/14], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 21 2008 *) PROG (PARI) is(n)=ispseudoprime((15^n-1)/14) \\ Charles R Greathouse IV, Apr 29 2015 CROSSREFS Cf. A059802, A062647, A003525. Sequence in context: A139854 A194578 A185632 * A246994 A142184 A199348 Adjacent sequences:  A006030 A006031 A006032 * A006034 A006035 A006036 KEYWORD nonn,hard,more AUTHOR EXTENSIONS a(7) from Julien Peter Benney (jpbenney(AT)ftml.net), Apr 27 2007 a(8) corresponds to a probable prime discovered by Paul Bourdelais, Mar 15 2010 a(9) corresponds to a probable prime discovered by Paul Bourdelais, Jan 14 2015 a(10) corresponds to a probable prime discovered by Paul Bourdelais, Apr 22 2019 STATUS approved

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Last modified December 13 06:26 EST 2019. Contains 329968 sequences. (Running on oeis4.)