A (1,3) Somos-4 sequence.

Terms

a(0) =1a(1) =2a(2) =5a(3) =17a(4) =109a(5) =706a(6) =9529a(7) =149057a(8) =3464585a(9) =141172802a(10) =5987285341a(11) =540281496721