a(n) = binomial(n, floor((n-6)/2)).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =1a(8) =8a(9) =9a(10) =45a(11) =55a(12) =220a(13) =286a(14) =1001a(15) =1365a(16) =4368a(17) =6188a(18) =18564a(19) =27132a(20) =77520a(21) =116280a(22) =319770a(23) =490314a(24) =1307504a(25) =2042975a(26) =5311735a(27) =8436285a(28) =21474180a(29) =34597290