This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A111023 #20 Jan 17 2019 13:44:08
%S A111023 1,2,3,4,6,8,16,20,27,115,180,274,576,1111,2404,5127,8082,9514,12808,
%T A111023 14752,15926,22670,37432,41988,53707,72595,92742
%N A111023 Integers n such that 9*10^n + 11 is a prime number.
%C A111023 See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "90w11".
%C A111023 a(28) > 10^5. - _Robert Price_, Jan 28 2017
%H A111023 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/">List of near-repdigit-related prime numbers</a>.
%H A111023 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%e A111023 n = 6 is a member because 9*10^6 + 11 = 9*1000000 + 11 = 9000011, which is prime.
%t A111023 Do[If[PrimeQ[9*10^n+11],Print[n]],{n,1,1300}] (* _Zak Seidov_, Sep 14 2006 *)
%Y A111023 Cf. A100275 = numbers n such that 9*10^n-11 is prime.
%Y A111023 Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054, A110980.
%K A111023 more,nonn
%O A111023 1,2
%A A111023 Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005
%E A111023 Edited by _N. J. A. Sloane_, Apr 11 2008
%E A111023 a(16)-a(22) from _Ray Chandler_, Dec 23 2010
%E A111023 a(23)-a(27) from _Robert Price_, Jan 28 2017