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 A035066 #14 Oct 08 2019 08:40:01
%S A035066 2,3,3,5,7,11,13,19,23,29,31,37,41,47,53,67,79,97,101,127,131,137,139,
%T A035066 149,167,173,179,181,191,193,197,199,227,229,233,239,257,263,281,283,
%U A035066 307,337,359,373,389,401,431,443,457,467,479,491,503,541,563,571,593
%N A035066 Prime lengths of factorials: see A035065.
%H A035066 Giovanni Resta, <a href="/A035066/b035066.txt">Table of n, a(n) for n = 1..10000</a>
%t A035066 Select[Table[IntegerLength[n!],{n,500}],PrimeQ] (* _Harvey P. Dale_, May 03 2015 *)
%Y A035066 Cf. A000142, A035065.
%K A035066 nonn,base
%O A035066 1,1
%A A035066 _Patrick De Geest_, Nov 15 1998
%E A035066 Offset changed to 1 by _Giovanni Resta_, Oct 08 2019