a(n) = (9n^4 - 18n^3 + 18n^2 - 9n + 2)/2.

Terms

a(0) =1a(1) =28a(2) =190a(3) =703a(4) =1891a(5) =4186a(6) =8128a(7) =14365a(8) =23653a(9) =36856a(10) =54946a(11) =79003a(12) =110215a(13) =149878a(14) =199396a(15) =260281a(16) =334153a(17) =422740a(18) =527878a(19) =651511a(20) =795691a(21) =962578a(22) =1154440a(23) =1373653a(24) =1622701a(25) =1904176a(26) =2220778a(27) =2575315a(28) =2970703a(29) =3409966