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 A046277 #23 Jan 16 2025 19:36:53
%S A046277 0,0,2,0,2,2,7,5,3,3,3,991,9001,227,8291,1307,209227,68742809,4023737,
%T A046277 164510040883,24329020081,510909421717,1240007,258520167388849,
%U A046277 4840173323,155112100433309,9146112660563,694504183521607,8344611713860501,6199373970195454361
%N A046277 Largest prime substring in n! (0 if none).
%H A046277 Paolo Xausa, <a href="/A046277/b046277.txt">Table of n, a(n) for n = 0..500</a>
%F A046277 a(n) = A047814(A000142(n)). - _Pontus von Brömssen_, Jan 16 2025
%e A046277 22! = 1{1240007}27777607680000.
%p A046277 a:= n-> (s-> max(0, select(isprime, {seq(seq(parse(
%p A046277 s[i..j]), i=1..j), j=1..length(s))})))(""||(n!)):
%p A046277 seq(a(n), n=0..30); # _Alois P. Heinz_, Jan 16 2025
%t A046277 A046277[n_] := Module[{d = IntegerDigits[n!/10^IntegerExponent[n!, 10]], len, s}, len = Length[d]; While[len > 0 && (s = Select[Map[FromDigits, Partition[d, len, 1]], IntegerLength[#] == len && PrimeQ[#] &]) == {}, len--]; Max[0, s]];
%t A046277 Array[A046277, 30, 0] (* _Paolo Xausa_, Jan 16 2025 *)
%Y A046277 Cf. A000142, A046276, A047814.
%K A046277 nonn,base
%O A046277 0,3
%A A046277 _Patrick De Geest_, Jun 15 1998
%E A046277 a(28)-a(29) from _Pontus von Brömssen_, Jan 16 2025