a(n) = n*(n + 1)*(n^2 + n + 2)/4.

Terms

a(0) =0a(1) =2a(2) =12a(3) =42a(4) =110a(5) =240a(6) =462a(7) =812a(8) =1332a(9) =2070a(10) =3080a(11) =4422a(12) =6162a(13) =8372a(14) =11130a(15) =14520a(16) =18632a(17) =23562a(18) =29412a(19) =36290a(20) =44310a(21) =53592a(22) =64262a(23) =76452a(24) =90300a(25) =105950a(26) =123552a(27) =143262a(28) =165242a(29) =189660