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 A005539 Numbers k such that 10*3^k + 1 is prime. (Formerly M2337) 4
 0, 1, 3, 4, 7, 9, 12, 18, 22, 102, 112, 157, 162, 289, 619, 763, 1389, 1783, 1882, 3294, 3567, 13297, 14932, 18954, 19612, 23598, 33882, 66874, 70546, 86568, 187626, 190738 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(33) > 2*10^5. - Robert Price, Mar 16 2014 All terms are verified primes (i.e., not merely probable primes). - Robert Price, Mar 16 2014 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. MATHEMATICA Do[ If[ PrimeQ[ 10*3^n + 1], Print[n]], {n, 0, 6810}] PROG (MAGMA) [n: n in [0..3567] | IsPrime(10*3^n + 1) ]; // Vincenzo Librandi, Sep 26 2012 (PARI) is(n)=ispseudoprime(10*3^n+1) \\ Charles R Greathouse IV, Feb 20 2017 CROSSREFS Sequence in context: A248358 A244952 A140402 * A253060 A203623 A053099 Adjacent sequences:  A005536 A005537 A005538 * A005540 A005541 A005542 KEYWORD hard,nonn AUTHOR EXTENSIONS More terms from Robert G. Wilson v, Sep 07 2000 a(1)=0 added and typo in Mathematica program fixed by Vincenzo Librandi, Sep 26 2012 a(22)-a(32) from Robert Price, Mar 16 2014 STATUS approved

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Last modified January 29 10:34 EST 2020. Contains 331337 sequences. (Running on oeis4.)