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 A135108 #23 Sep 08 2022 08:45:32 %S A135108 2,3,4,6,8,12,20,72,196,676,1528,1923,5244,5379,6308,21222,81778 %N A135108 Integers n such that 10^n+39 is a prime number. %H A135108 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/">List of near-repdigit-related prime numbers</a>. (See primecount.txt for terms, primesize.txt for discovery details, including probable or proved primes - search on "10039") %H A135108 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>. %e A135108 6 is a member: 10^6+39 = 1000000+39 = 1000039, which is a prime number. %t A135108 Select[Range[2000], PrimeQ[10^# + 39] &] (* _G. C. Greubel_, Sep 23 2016 *) %o A135108 (Magma) [n: n in [0..500] |IsPrime(10^n+39)]; // _Vincenzo Librandi_, Sep 24 2016 %Y A135108 Cf. A095688, A108052, A108050, A108312, A107083, A108049, A108054. %K A135108 more,nonn %O A135108 1,1 %A A135108 Julien Peter Benney (jpbenney(AT)gmail.com), Feb 12 2008 %E A135108 a(11)-a(12) from _Harvey P. Dale_, May 25 2008 %E A135108 a(13)-a(16) from _Robert Price_, Jan 30 2010 %E A135108 Edited by _Ray Chandler_, Dec 23 2010 %E A135108 a(17) from _Robert Price_, Mar 03 2011