1,1

No others less than 8011. - Julien Peter Benney (jpbenney(AT)ftml.net), Aug 15 2004

a(9) = 9511 was found by Richard Fischer Dec 15 2004. - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.

Ribenboim, Paulo; "The Book Of Prime Number Records"; published 1989 by Springer-Verlag; pages 350-354.

H. Lifchitz, Mersenne and Fermat primes field

lst={}; Do[If[PrimeQ[(19^n-1)/18], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 21 2008]

Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034. Cf. A127995, A127996, A127997, A127998, A127999, A128000, A098438, A128002, A128003, A128004, A128005.

Sequence in context: A096787 A104006 A117065 this_sequence A104485 A141184 A033212

Adjacent sequences: A006032 A006033 A006034 this_sequence A006036 A006037 A006038

nonn

N. J. A. Sloane (njas(AT)research.att.com).

One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008