a(n) = 1 + Sum_{k=0..n-4} a(k) * a(n-k-4).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =4a(7) =5a(8) =8a(9) =13a(10) =20a(11) =29a(12) =45a(13) =73a(14) =118a(15) =185a(16) =293a(17) =475a(18) =778a(19) =1263a(20) =2047a(21) =3345a(22) =5512a(23) =9085a(24) =14957a(25) =24683a(26) =40918a(27) =67987a(28) =113016a(29) =188053