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 A028366 #19 May 17 2019 06:04:36 %S A028366 1,1,6,5040,1307674368000,8222838654177922817725562880000000, %T A028366 1982608315404440064116146708361898137544773690227268628106279599612729753600000000000000 %N A028366 a(n) = (2^n - 1)!. %H A028366 I. Strazdins, <a href="https://doi.org/10.1023/A:1005769927571">Universal affine classification of Boolean functions</a>, Acta Applic. Math. 46 (1997), 147-167. %t A028366 (2^Range[0, 6] - 1)! (* _Alonso del Arte_, Dec 24 2016 *) %o A028366 (PARI) for(n=0, 10, print1((2^n -1)!, ", ")) \\ _G. C. Greubel_, Dec 25 2016 %Y A028366 Cf. A000142, A000225. %K A028366 nonn,easy %O A028366 0,3 %A A028366 _N. J. A. Sloane_