a(n) = Sum_{k=0..floor((2*n+1)/5)} binomial(2*k+1,2*n-5*k+1).

Terms

a(0) =1a(1) =0a(2) =1a(3) =3a(4) =0a(5) =5a(6) =10a(7) =2a(8) =21a(9) =35a(10) =16a(11) =84a(12) =127a(13) =91a(14) =331a(15) =475a(16) =451a(17) =1299a(18) =1821a(19) =2080a(20) =5100a(21) =7116a(22) =9192a(23) =20074a(24) =28201a(25) =39529a(26) =79292a(27) =112864a(28) =166922a(29) =314413