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 A005540 Numbers k such that 4*3^k - 1 is prime. (Formerly M2422) 4
 0, 1, 3, 5, 7, 15, 45, 95, 235, 463, 733, 1437, 1583, 1677, 1803, 4163, 4765, 9219, 9959, 25477, 26059, 41539, 54195, 65057, 74977, 116589, 192289, 311835, 350767, 353635, 416337, 423253 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS H. C. Williams and C. R. Zarnke, Some prime numbers of the forms 2*3^n+1 and 2*3^n-1, Math. Comp., 26 (1972), 995-998. PROG (PARI) is(n)=ispseudoprime(4*3^n-1) \\ Charles R Greathouse IV, Feb 20 2017 CROSSREFS Sequence in context: A303027 A217615 A050553 * A155802 A080741 A247356 Adjacent sequences:  A005537 A005538 A005539 * A005541 A005542 A005543 KEYWORD nonn,hard AUTHOR EXTENSIONS More terms from Robert G. Wilson v and from Jud McCranie More terms from Borys Jaworski, Feb 13 2010 0 added by Vincenzo Librandi, Sep 26 2012 STATUS approved

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Last modified October 23 09:45 EDT 2019. Contains 328345 sequences. (Running on oeis4.)