a(n) = binomial(floor(n/2),4) + (ceiling(n/2)-3)*binomial(floor(n/2),3).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =1a(8) =5a(9) =9a(10) =25a(11) =35a(12) =75a(13) =95a(14) =175a(15) =210a(16) =350a(17) =406a(18) =630a(19) =714a(20) =1050a(21) =1170a(22) =1650a(23) =1815a(24) =2475a(25) =2695a(26) =3575a(27) =3861a(28) =5005a(29) =5369