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 A131057 #8 Aug 28 2022 23:15:36
%S A131057 0,2,1,2,7,1,2,1,5,3,1,19,11,1,19,19,11,1,19,23,1,1,47,1,1,29,3,29,2,
%T A131057 59,73,1,43,1,13,17,41,1,2,5,3,53,79,7,1,53,23,1,13,13,61,7,59,61,7,
%U A131057 31,1,89,107,103,67,47,103,19,43,1,71,11,7,83,79,67,71
%N A131057 Least nonnegative k such that n!-k is semiprime.
%C A131057 Semiprime analog of A033933. After n = 3, a(n) is never again 0.
%F A131057 a(n) = Min_{k such that n!-k is in A001358 and k>=0}.
%e A131057 a(3) = 0 because 3! - 0 = 6 - 0 = 6 = 2 * 3.
%e A131057 a(4) = 2 because 4! - 2 = 24 - 2 = 22 = 2 * 11.
%e A131057 a(5) = 1 because 5! - 1 = 119 = 7 * 17.
%Y A131057 Cf. A001358, A033933, A356207.
%K A131057 nonn
%O A131057 3,2
%A A131057 _Jonathan Vos Post_, Sep 24 2007
%E A131057 More terms from _Jinyuan Wang_, Aug 28 2022