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

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =3a(5) =6a(6) =12a(7) =25a(8) =51a(9) =101a(10) =197a(11) =381a(12) =731a(13) =1392a(14) =2634a(15) =4958a(16) =9290a(17) =17337a(18) =32239a(19) =59760a(20) =110460a(21) =203651a(22) =374593a(23) =687567a(24) =1259597a(25) =2303449a(26) =4205493a(27) =7666560a(28) =13956532a(29) =25374108