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 A086654 #11 Apr 12 2025 01:41:08 %S A086654 1,5,4,9,20,14,40,28,434,10,1337,354,5370,6180,179472 %N A086654 Smallest number a(n) > n such that a(n)! contains n! as a substring. %C A086654 From _Michael S. Branicky_, Apr 11 2025: (Start) %C A086654 500000 < a(15..20), with lower values ruled out by exhaustive search; %C A086654 a(16) <= 80377420, a(17) <= 5770007, a(18) <= 674238256, with upper bound k achieved where A004154(k) ends with A004154(n). (End) %F A086654 a(10^m-1) = 10^m, m >= 0. - _Michael S. Branicky_, Apr 10 2025 %e A086654 a[5]=14 since 14!= 8717829_120_0. %Y A086654 Cf. A004154 %K A086654 nonn,base,hard,more %O A086654 0,2 %A A086654 _Erich Friedman_, Sep 11 2003 %E A086654 a(13)-a(14) from _Michael S. Branicky_, Apr 10 2025