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 A006990 M1541 #37 Nov 08 2017 19:34:24
%S A006990 2,5,23,113,719,5039,40289,362867,3628789,39916787,479001599,
%T A006990 6227020777,87178291199,1307674367953,20922789887947,355687428095941,
%U A006990 6402373705727959,121645100408831899,2432902008176639969,51090942171709439969,1124000727777607679927
%N A006990 Largest prime <= n!.
%C A006990 Conjecture: For n >= 2, n! - a(n) is 1 or a prime, see A033933. - _Amarnath Murthy_, Mar 19 2002
%C A006990 a(n) is the largest prime divisor of (n!)! of the sequence A000197. - _Stanislav Sykora_, Jul 14 2014
%D A006990 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006990 Donovan Johnson, <a href="/A006990/b006990.txt">Table of n, a(n) for n = 2..400</a>
%H A006990 R. G. Wilson v, <a href="/A006990/a006990.pdf">Letter to N. J. A. Sloane, Oct. 1993</a>
%t A006990 PrevPrime[ n_Integer ] := Module[ {k = n - 1}, While[ ! PrimeQ[ k ], k-- ]; k ]; Table[ PrevPrime[ n! ], {n, 3, 25} ]
%t A006990 Join[{2},NextPrime[Range[3,30]!,-1]] (* _Harvey P. Dale_, Jan 24 2014 *)
%Y A006990 Cf. A000142, A007917.
%K A006990 nonn
%O A006990 2,1
%A A006990 _N. J. A. Sloane_, _Robert G. Wilson v_
%E A006990 More terms from _Jud McCranie_; also from _Robert G. Wilson v_, Jan 03 2001