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 A079907 Numbers n such that 11*12^n -1 is prime. 15
 1, 2, 21, 25, 33, 54, 78, 235, 1566, 2273, 2310, 4121, 7775, 42249, 105974, 138961 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(17) > 2*10^5. - Robert Price, Mar 20 2015 REFERENCES R. K. Guy, Unsolved Problems in Theory of Numbers, Section A3. LINKS Steven Harvey, Williams Primes H. C. Williams, The primality of certain integers of the form 2Ar^n - 1, Acta Arith. 39 (1981), 7-17. MATHEMATICA Do[ If[ PrimeQ[11*12^n - 1], Print[n]], {n, 1, 2000}] Select[Range[10000], PrimeQ[(11 12^# - 1)] &] (* Vincenzo Librandi, Mar 21 2015 *) PROG (PARI) for(n=1, 2000, if(isprime(11*12^n-1), print1(n, ", "))) (MAGMA) [n: n in [1..600]| IsPrime(11*12^n - 1)]; // Vincenzo Librandi, Mar 21 2015 CROSSREFS Cf. A003307, A002235, A046865, A079906, A046866, A001771, A005541, A056725, A046867. Sequence in context: A041513 A135053 A042565 * A075715 A326735 A294377 Adjacent sequences:  A079904 A079905 A079906 * A079908 A079909 A079910 KEYWORD nonn,hard AUTHOR Robert G. Wilson v, Jan 16 2003 EXTENSIONS More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008 a(13)-a(16) from Robert Price, Mar 20 2015 STATUS approved

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Last modified June 7 05:20 EDT 2020. Contains 334837 sequences. (Running on oeis4.)