a(n) = 70*binomial(n,8) + 2*binomial(n,4) + 1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =11a(6) =31a(7) =71a(8) =211a(9) =883a(10) =3571a(11) =12211a(12) =35641a(13) =91521a(14) =212213a(15) =453181a(16) =904541a(17) =1706461a(18) =3069181a(19) =5298493a(20) =8827591a(21) =14256271a(22) =22398531a(23) =34339691a(24) =51504223a(25) =75735551a(26) =109389151a(27) =155440351a(28) =217608301a(29) =300497653