A004168 a(n+1) = a(n)*(a(n)+1).

3, 12, 156, 24492, 599882556, 359859081592975692, 129498558604939936868397356895854556, 16769876680757063368089314196389622249367851612542961252860614401811692

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

The next term (a(8)) has 141 digits. - Harvey P. Dale, Jul 02 2021

Crossrefs

Cf. A000058, A007018.

Programs

Magma

[n eq 1 select 3 else  Self(n-1)*(Self(n-1)+1): n in [1..10]]; // Vincenzo Librandi, Feb 23 2016

Maple

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

Mathematica

a = {3}; Do[AppendTo[a, a[[n - 1]] (a[[n - 1]] + 1)], {n, 2, 8}]; a (* Michael De Vlieger, Feb 23 2016 *)
NestList[#(#+1)&,3,7] (* Harvey P. Dale, Jul 02 2021 *)

Formula

a(n) = A082732(n+3) - 1. - Max Alekseyev, Aug 09 2019

Extensions

a(7) from Vincenzo Librandi, Feb 23 2016