a(n) = 5*binomial(n,6) + 2*binomial(n,4).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =10a(6) =35a(7) =105a(8) =280a(9) =672a(10) =1470a(11) =2970a(12) =5610a(13) =10010a(14) =17017a(15) =27755a(16) =43680a(17) =66640a(18) =98940a(19) =143412a(20) =203490a(21) =283290a(22) =387695a(23) =522445a(24) =694232a(25) =910800a(26) =1181050a(27) =1515150a(28) =1924650a(29) =2422602