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 A265383 Numbers k such that 10^k * (10^k - 1) - 1 is prime. 1
 1, 6, 9, 154, 253, 1114, 1390, 2618, 5611, 12871, 15286, 108609, 132574, 164369, 188484 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The primes arising from this construction (e.g., 999998999999) are among the primes counted in A266148. In particular, it follows that A266148(a(n)) > 0. - David A. Corneth, May 19 2016 a(16) > 188484. - Ben Meekins, Sep 08 2018 LINKS Table of n, a(n) for n=1..15. Brady Haran and Simon Pampena, Glitch Primes and Cyclops Numbers, Numberphile video (2015). M. Kamada, Near-repdigit-related prime numbers EXAMPLE 6 is in the sequence because 10^12 - 10^6 - 1 = 999998999999 is prime. MATHEMATICA Select[Range[15000], PrimeQ[10^# (10^# - 1) - 1] &] (* Vincenzo Librandi, Dec 08 2015 *) PROG (PARI) for(n=1, 9999, if(ispseudoprime(10^n*(10^n-1)-1), print1(n", "))) (Magma) [n: n in [0..200] | IsPrime(10^n*(10^n-1)-1)]; // Vincenzo Librandi, Dec 08 2015 CROSSREFS Cf. similar sequences listed in A265481. A098845: Similar sequence in base 2. A183187: Numbers k such that 10^(2k+1)-10^k-1 is prime, palindromic. A266148: Number of n-digit primes in which n-1 of the digits are 9's. Sequence in context: A191011 A351734 A053490 * A367881 A367879 A264375 Adjacent sequences: A265380 A265381 A265382 * A265384 A265385 A265386 KEYWORD nonn,more AUTHOR Serge Batalov, Dec 07 2015 EXTENSIONS a(11) from Kazuyoshi Asao, Feb 11 2002 a(12) from Serge Batalov, Dec 25 2015 a(13) from Ben Meekins, Feb 16 2016 a(14) from Ben Meekins, Dec 17 2016 a(15) from Ben Meekins, Sep 08 2018 STATUS approved

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Last modified August 12 06:37 EDT 2024. Contains 375085 sequences. (Running on oeis4.)