a(n) = Sum_{k=0..floor(n/3)} binomial(k,2*n-6*k).

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =0a(5) =0a(6) =1a(7) =1a(8) =0a(9) =1a(10) =3a(11) =0a(12) =1a(13) =6a(14) =1a(15) =1a(16) =10a(17) =5a(18) =1a(19) =15a(20) =15a(21) =2a(22) =21a(23) =35a(24) =8a(25) =28a(26) =70a(27) =29a(28) =37a(29) =126