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 A199819 #14 Apr 21 2025 17:07:03 %S A199819 19,271,5217031,68618940391,8649148282327007911, %T A199819 95289871302753755165078396311 %N A199819 Primes of the form 10^k-9^k. %H A199819 Vincenzo Librandi, <a href="/A199819/b199819.txt">Table of n, a(n) for n = 1..9</a> %F A199819 a(n) = A016189(A062576(n)). - _Michel Marcus_, Apr 21 2025 %t A199819 Select[10^Range[3000]-9^Range[3000],PrimeQ] %o A199819 (Magma) [ a: n in [0..400] | IsPrime(a) where a is 10^n-9^n ]; %Y A199819 Cf. A016189, A062576 %K A199819 nonn %O A199819 1,1 %A A199819 _Vincenzo Librandi_, Nov 21 2011