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 A108049 #31 Aug 09 2025 20:07:39 %S A108049 1,5,37,253,1129,1441,35393 %N A108049 Integers k such that 10^k + 43 is a prime number. %C A108049 a(8) > 10^5. - _Robert Price_, Nov 01 2013 %C A108049 See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "10043". %H A108049 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/">List of near-repdigit-related prime numbers</a>. %H A108049 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>. %e A108049 k=5 is a term because 10^5 + 43 = 100043, which is prime. %t A108049 Select[Range[2*10^3],PrimeQ[10^#+43]&] (* _Vladimir Joseph Stephan Orlovsky_, Apr 29 2008 *) %o A108049 (PARI) is(n)=ispseudoprime(10^n+43) \\ _Charles R Greathouse IV_, Apr 28 2015 %Y A108049 Cf. A049054, A088274, A088275. %K A108049 nonn,more,hard %O A108049 1,2 %A A108049 Julien Peter Benney (jpbenney(AT)ftml.net), Jun 01 2005 %E A108049 a(7)=35393 from _Robert Price_, Mar 16 2010 %E A108049 Edited by _Ray Chandler_, Dec 23 2010