a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 0, 2, 1, 0.

Terms

a(0) =0a(1) =2a(2) =1a(3) =0a(4) =2a(5) =1a(6) =4a(7) =6a(8) =10a(9) =24a(10) =36a(11) =85a(12) =152a(13) =310a(14) =638a(15) =1232a(16) =2620a(17) =5194a(18) =10840a(19) =22332a(20) =46004a(21) =96528a(22) =199816a(23) =420365a(24) =880112a(25) =1851366a(26) =3908854a(27) =8245536a(28) =17482220a(29) =37049662