A (1,1) Somos-4 sequence.

Terms

a(0) =0a(1) =1a(2) =1a(3) =-1a(4) =2a(5) =3a(6) =1a(7) =-11a(8) =-16a(9) =35a(10) =-129a(11) =-299a(12) =-386a(13) =3977a(14) =8063a(15) =-42489a(16) =269344a(17) =1000009a(18) =3727745a(19) =-47166649a(20) =-123526014a(21) =1764203419a(22) =-18228952703a(23) =-113727892147