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 A004168 #28 Oct 24 2023 20:37:35
%S A004168 3,12,156,24492,599882556,359859081592975692,
%T A004168 129498558604939936868397356895854556,
%U A004168 16769876680757063368089314196389622249367851612542961252860614401811692
%N A004168 a(n+1) = a(n)*(a(n)+1).
%C A004168 The next term (a(8)) has 141 digits. - _Harvey P. Dale_, Jul 02 2021
%F A004168 a(n) = A082732(n+3) - 1. - _Max Alekseyev_, Aug 09 2019
%p A004168 A004168 := proc(n) option remember; if n=0 then 3 else A004168(n-1)*(A004168(n-1)+1); fi; end;
%t A004168 a = {3}; Do[AppendTo[a, a[[n - 1]] (a[[n - 1]] + 1)], {n, 2, 8}]; a (* _Michael De Vlieger_, Feb 23 2016 *)
%t A004168 NestList[#(#+1)&,3,7] (* _Harvey P. Dale_, Jul 02 2021 *)
%o A004168 (Magma) [n eq 1 select 3 else Self(n-1)*(Self(n-1)+1): n in [1..10]]; // _Vincenzo Librandi_, Feb 23 2016
%Y A004168 Cf. A000058, A007018.
%K A004168 nonn,easy
%O A004168 0,1
%A A004168 _N. J. A. Sloane_
%E A004168 a(7) from _Vincenzo Librandi_, Feb 23 2016