a(n) = binomial(n, floor((n-5)/2)).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =1a(7) =7a(8) =8a(9) =36a(10) =45a(11) =165a(12) =220a(13) =715a(14) =1001a(15) =3003a(16) =4368a(17) =12376a(18) =18564a(19) =50388a(20) =77520a(21) =203490a(22) =319770a(23) =817190a(24) =1307504a(25) =3268760a(26) =5311735a(27) =13037895a(28) =21474180a(29) =51895935