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 A137577 #5 Mar 30 2012 18:50:59
%S A137577 9,9,9,9,9,9,9,9,9,9,9,7,8,9,6,9,6,1,9,9,5,8,9,9,5,7,7,9,9,2,7,9,4,7,
%T A137577 8,8,6,8,8,6,6,9,7,9,9,8,7,7,9,9,9,9,9,1,6,8,2,7,7,5,5,1,4,5,7,1,5,7,
%U A137577 6,6,3,9,5,9,6,3,1,5,9,4,9,8,5,8,5,8,8,6,7,4,3,3,9,9,9,1,2,5,1,7,7
%N A137577 Largest of the least frequent digits in decimal representation of n!.
%C A137577 A137578(n) <= a(n).
%H A137577 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%e A137577 n=10: 10! = 3628800 => a(10) = Max{1,4,5,7,9} = 9;
%e A137577 n=11: 11! = 39916800 => a(11) = Max{2,4,5,7} = 7.
%Y A137577 Cf. A000142, A027869, A079680, A079714, A079684, A079688, A079690, A079691, A079692, A079693, A079694, A137579, A137580.
%K A137577 nonn,base
%O A137577 0,1
%A A137577 _Reinhard Zumkeller_, Jan 27 2008