a(n) = n * binomial(n-1, floor((n-1)/2)) = n * max_{i=0..n} binomial(n-1, i).

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =12a(5) =30a(6) =60a(7) =140a(8) =280a(9) =630a(10) =1260a(11) =2772a(12) =5544a(13) =12012a(14) =24024a(15) =51480a(16) =102960a(17) =218790a(18) =437580a(19) =923780a(20) =1847560a(21) =3879876a(22) =7759752a(23) =16224936a(24) =32449872a(25) =67603900a(26) =135207800a(27) =280816200a(28) =561632400a(29) =1163381400