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 A108052 #35 Aug 09 2025 22:35:57 %S A108052 1,3,5,7,10,11,17,59,81,108,574,629,1069,1759,2063,2682,9174,40929, %T A108052 42457,66033 %N A108052 Integers k such that 10^k+19 is a prime number. %C A108052 Verified terms through 9174. - _Robert Price_, May 24 2010 %C A108052 See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "10019". %C A108052 No other terms <= 100,000. - _Robert Price_, Mar 03 2011 %H A108052 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/">List of near-repdigit-related prime numbers</a>. %H A108052 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>. %e A108052 n = 7 we have 10^7+19 = 10000000+19 = 10000019, which is prime. %t A108052 Select[Range[2*10^3],PrimeQ[10^#+19]&] (* _Vladimir Joseph Stephan Orlovsky_, Apr 29 2008 *) %o A108052 (PARI) is(n)=ispseudoprime(10^n+19) \\ _Charles R Greathouse IV_, Apr 28 2015 %Y A108052 Cf. A049054, A088274, A088275, A095688. %K A108052 more,nonn,hard %O A108052 1,2 %A A108052 Julien Peter Benney (jpbenney(AT)ftml.net), Jun 01 2005 %E A108052 a(17)=9174 from _Ryan Propper_, Jan 02 2008 %E A108052 Edited by _Ray Chandler_, Dec 23 2010 %E A108052 a(18)=40929 and a(19)=42457 from _Robert Price_, Dec 27 2010 %E A108052 a(20)=66033 from _Robert Price_, Jan 09 2011