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 A057157 #14 Sep 08 2022 08:45:02
%S A057157 0,2,232,16736896,18446723150919663616,
%T A057157 1461501637330639787366751139186115801643772542976
%N A057157 Number of non-invertible functions from {0,1}^n to {0,1}^n.
%H A057157 Vincenzo Librandi, <a href="/A057157/b057157.txt">Table of n, a(n) for n = 0..10</a>
%F A057157 a(n) = (2^n)^(2^n) - (2^n)! = A057156(n) - A000722(n) = A036679(A000079(n)).
%t A057157 Table[(2^n)^(2^n) - (2^n)!, {n,0,5}] (* _G. C. Greubel_, Nov 08 2018 *)
%o A057157 (Magma) [(2^n)^(2^n)-Factorial(2^n): n in [0..5]]; // _Vincenzo Librandi_, Aug 22 2011
%o A057157 (PARI) vector(6,n,n--; (2^n)^(2^n) - (2^n)!) \\ _G. C. Greubel_, Nov 08 2018
%Y A057157 Cf. A057156, A000722, A036679, A000079.
%K A057157 nonn,easy
%O A057157 0,2
%A A057157 _Henry Bottomley_, Aug 15 2000