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 A108519 #10 May 21 2024 05:29:23
%S A108519 11,271,6701,40471
%N A108519 a(n) is the smallest natural number m such that (10^n)! - m is prime.
%C A108519 If a(n) is composite then a(n)>10^(2n)+2*10^n. Conjecture: All terms are noncomposite numbers.
%C A108519 (10^4)!-40471 is a probable prime. - _Jason Yuen_, May 20 2024
%F A108519 a(n) = A033933(10^n). - _Jason Yuen_, May 20 2024
%e A108519 a(3)=6701 because (10^3)!-6701 is prime and for 0<m<6701 1000!-m is
%e A108519 composite.
%t A108519 a[n_] := (For[m = 1, ! PrimeQ[(10^n)! - m], m++ ]; m); Do[Print[a[n]], {n, 3}]
%Y A108519 Cf. A108518, A033933.
%K A108519 more,nonn,hard
%O A108519 1,1
%A A108519 _Farideh Firoozbakht_, Jul 10 2005
%E A108519 a(4) from _Jason Yuen_, May 20 2024