Sum C(n-4k,k-1), k=0..floor(n/5).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =1a(7) =1a(8) =1a(9) =1a(10) =3a(11) =4a(12) =5a(13) =6a(14) =7a(15) =11a(16) =15a(17) =20a(18) =26a(19) =33a(20) =45a(21) =60a(22) =80a(23) =106a(24) =139a(25) =185a(26) =245a(27) =325a(28) =431a(29) =570