Sum C(n-3k,k-1), k=0..floor(n/4).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =1a(7) =1a(8) =3a(9) =4a(10) =5a(11) =6a(12) =10a(13) =14a(14) =19a(15) =25a(16) =36a(17) =50a(18) =69a(19) =94a(20) =131a(21) =181a(22) =250a(23) =344a(24) =476a(25) =657a(26) =907a(27) =1251a(28) =1728a(29) =2385