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 A329063 #52 Nov 05 2019 10:58:50 %S A329063 1,2,4,28,304888344611713860501504000028 %N A329063 a(n) = a(n-1)! + a(n-1) with a(1)=1. %C A329063 The next term is too large to include, since it has about 8.85695956*10^30 digits. %C A329063 No term can be represented by a sum of three positive squares, because a(4) and the following terms can all be written as 4*(8*k+7) for k>=0. %F A329063 a(n) = a(n-1)! + a(n-1) %e A329063 a(3) = a(3-1)! + a(3-1) = a(2)! + a(2) = 4. %t A329063 a[1]=1; a[n_] := a[n-1]! + a[n-1]; Array[a, 5] (* _Giovanni Resta_, Nov 03 2019 *) %Y A329063 Cf. A000408 (sums of 3 squares). %K A329063 nonn %O A329063 1,2 %A A329063 _Ananthakrishna Kaithalayil_, Nov 02 2019 %E A329063 Edited by _N. J. A. Sloane_, Nov 03 2019