a(n) = (7*n^6 - 21*n^5 + 55*n^4 - 75*n^3 + 70*n^2 - 36*n + 8)/8.

Terms

a(0) =1a(1) =1a(2) =34a(3) =370a(4) =2179a(5) =8791a(6) =27586a(7) =72514a(8) =167245a(9) =348949a(10) =672706a(11) =1216546a(12) =2087119a(13) =3425995a(14) =5416594a(15) =8291746a(16) =12341881a(17) =17923849a(18) =25470370a(19) =35500114a(20) =48628411a(21) =65578591a(22) =87193954a(23) =114450370a(24) =148469509a(25) =190532701a(26) =242095426a(27) =304802434a(28) =380503495a(29) =471269779