%I #28 Oct 24 2023 20:37:35

%S 3,12,156,24492,599882556,359859081592975692,

%T 129498558604939936868397356895854556,

%U 16769876680757063368089314196389622249367851612542961252860614401811692

%N a(n+1) = a(n)*(a(n)+1).

%C The next term (a(8)) has 141 digits. - _Harvey P. Dale_, Jul 02 2021

%F a(n) = A082732(n+3) - 1. - _Max Alekseyev_, Aug 09 2019

%p A004168 := proc(n) option remember; if n=0 then 3 else A004168(n-1)*(A004168(n-1)+1); fi; end;

%t a = {3}; Do[AppendTo[a, a[[n - 1]] (a[[n - 1]] + 1)], {n, 2, 8}]; a (* _Michael De Vlieger_, Feb 23 2016 *)

%t NestList[#(#+1)&,3,7] (* _Harvey P. Dale_, Jul 02 2021 *)

%o (Magma) [n eq 1 select 3 else Self(n-1)*(Self(n-1)+1): n in [1..10]]; // _Vincenzo Librandi_, Feb 23 2016

%Y Cf. A000058, A007018.

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_

%E a(7) from _Vincenzo Librandi_, Feb 23 2016