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 A046857 #11 Mar 07 2020 07:48:43 %S A046857 2,6,1120,36324288000,18272974787062050706056806400000, %T A046857 244766458691906180755079840538505942906762183978675139272380197483053056000000000000 %N A046857 a(n) = (2^n)!/(n!^2). %H A046857 C. S. Lorens, <a href="http://dx.doi.org/10.1109/PGEC.1964.263724">Invertible Boolean functions</a>, IEEE Trans. Electron. Computers, EC-13 (1964), 529-541. %H A046857 C. S. Lorens, <a href="/A000722/a000722.pdf">Invertible Boolean functions</a>, IEEE Trans. Electron. Computers, EC-13 (1964), 529-541. [Annotated scan of page 530 only] %K A046857 nonn,easy %O A046857 1,1 %A A046857 _N. J. A. Sloane_