The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A057472 Numbers k such that 2*6^k - 1 is prime. 7
 1, 2, 3, 4, 5, 12, 16, 26, 27, 36, 40, 45, 49, 52, 53, 75, 140, 150, 167, 245, 250, 755, 785, 825, 970, 1235, 1289, 1477, 1739, 1872, 1976, 1993, 2175, 4218, 7656, 10898, 13410, 13625, 15706, 33003, 44288, 45556, 48855, 60522, 62795, 98898, 118429, 153714 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(49) > 2*10^5. - Robert Price, Jan 06 2016 [Since a(39) was missing before, this a(49) should actually be a(50). - Jianing Song, Sep 22 2018] Numbers k such that A164559(k+1) is prime. LINKS MATHEMATICA Select[Range[1000], PrimeQ[2*6^# - 1] &] (* Giovanni Resta, May 19 2016 *) PROG (PARI) is(n)=ispseudoprime(2*6^n-1) \\ Charles R Greathouse IV, Feb 17 2017 (MAGMA) [n: n in [0..2000] |IsPrime(2*6^n - 1)]; // Vincenzo Librandi, Sep 23 2018 CROSSREFS Cf. A164559. Sequence in context: A329793 A103651 A093713 * A333390 A117577 A109849 Adjacent sequences:  A057469 A057470 A057471 * A057473 A057474 A057475 KEYWORD nonn AUTHOR Robert G. Wilson v, Sep 10 2000 EXTENSIONS More terms from Pierre CAMI, Jun 16 2006 Edited by Michel Marcus, Jan 06 2012 a(41)-a(48) from Robert Price, Jan 06 2016 Missing a(39) from Pierre CAMI, May 19 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 22 10:29 EDT 2021. Contains 347606 sequences. (Running on oeis4.)