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 A181899 #15 Jun 22 2019 10:49:21
%S A181899 2,5,12,35,96,288,945,3150,10800,39312,147420,571536,2286144,9424800,
%T A181899 39984000,174283200,779688000,3573570000,16761064320,80379048750,
%U A181899 393826406400,1969132032000,10040487256800,52174220175000,276080056560000,1486750296281250
%N A181899 Largest divisor of n!/4 which is less than sqrt(n!)/2.
%C A181899 Comment from A038202: Let f=n!/4 and let a(n) be the largest divisor of f such that a(n) < sqrt(f). Then A038202(n) = f/a(n) - a(n). The greatest k such that n!+k^2 is a square is f-1. The number of k for which n!+k^2 is a square is A038548(f). - _T. D. Noe_, Nov 02 2004
%t A181899 Table[f = n!/4; Select[Divisors[f], # <= Sqrt[f] &][[-1]], {n, 4, 20}]
%Y A181899 Cf. A038202, A138196, A139151, A181892, A181893.
%K A181899 nonn
%O A181899 4,1
%A A181899 _Artur Jasinski_, Mar 31 2012