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%I #91 Sep 08 2022 08:46:14
%S 1,6,9,154,253,1114,1390,2618,5611,12871,15286,108609,132574,164369,
%T 188484
%N Numbers n such that 10^n * (10^n - 1) - 1 is prime.
%C The primes arising from this construction (e.g., 999998999999) are among the primes being counted in A266148. In particular, it follows that A266148(a(n)) > 0. - _David A. Corneth_, May 19 2016
%C a(16) > 188484. - _Ben Meekins_, Sep 08 2018
%H Brady Haran and Simon Pampena, <a href="https://www.youtube.com/watch?v=HPfAnX5blO0">Glitch Primes and Cyclops Numbers</a>, Numberphile video (2015)
%H M. Kamada, <a href="https://stdkmd.net/nrr/prime/">Near-repdigit-related prime numbers</a>
%e 6 is in the sequence because 10^12 - 10^6 - 1 = 999998999999 is prime.
%t Select[Range[15000], PrimeQ[10^# (10^# - 1) - 1] &] (* _Vincenzo Librandi_, Dec 08 2015 *)
%o (PARI) for(n=1,9999,if(ispseudoprime(10^n*(10^n-1)-1),print1(n", ")))
%o (Magma) [n: n in [0..200] | IsPrime(10^n*(10^n-1)-1)]; // _Vincenzo Librandi_, Dec 08 2015
%Y Cf. similar sequences listed in A265481.
%Y A098845: Similar sequence in base 2.
%Y A183187: Numbers n such that 10^(2n+1)-10^n-1 is prime, palindromic.
%Y A266148: Number of n digit primes in which n-1 of the digits are 9's.
%K nonn,more
%O 1,2
%A _Serge Batalov_, Dec 07 2015
%E a(11) from Kazuyoshi Asao, Feb 11 2002
%E a(12) from _Serge Batalov_, Dec 25 2015
%E a(13) from _Ben Meekins_, Feb 16 2016
%E a(14) from _Ben Meekins_, Dec 17 2016
%E a(15) from _Ben Meekins_, Sep 08 2018
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