a(0) = 1, a(1) = 0, a(2) = 1; a(n) = a(n-1) + Sum_{k=0..n-3} a(k) * a(n-k-3).

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =2a(5) =4a(6) =8a(7) =13a(8) =25a(9) =49a(10) =91a(11) =177a(12) =349a(13) =681a(14) =1349a(15) =2693a(16) =5377a(17) =10806a(18) =21820a(19) =44163a(20) =89721a(21) =182868a(22) =373616a(23) =765341a(24) =1571551a(25) =3233690a(26) =6667242a(27) =13772469a(28) =28498419a(29) =59065838