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 A127426 #7 Jan 24 2024 09:57:24
%S A127426 0,0,0,0,8,64,504,4132,36224,343197,3528800,39382654,476015616,
%T A127426 6209617492,87072877696,1307012632486,20918494920704,355658666311252,
%U A127426 6402175346437632,121643693845767057,2432891768176640000,51090865734892274539,1124000143459306268672
%N A127426 a(n) = n! - ceiling(n^(n/2)).
%C A127426 Theorem: n! > n^(n/2) for n >= 2 [Cauchy].
%D A127426 D. S. Mitrinovic, Analytic Inequalities, Springer-Verlag, 1970; p. 192, 3.1.14.
%t A127426 Join[{0},Table[n!-Ceiling[n^(n/2)],{n,30}]] (* _Harvey P. Dale_, Jul 14 2018 *)
%K A127426 nonn
%O A127426 0,5
%A A127426 _N. J. A. Sloane_, Apr 02 2007