a(0) = ... = a(3) = 1; a(n) = a(n-4) + Sum_{k=0..n-5} a(k) * a(n-k-5).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =3a(7) =4a(8) =5a(9) =7a(10) =11a(11) =17a(12) =25a(13) =36a(14) =53a(15) =81a(16) =125a(17) =191a(18) =289a(19) =439a(20) =675a(21) =1046a(22) =1621a(23) =2506a(24) =3877a(25) =6023a(26) =9395a(27) =14681a(28) =22947a(29) =35890