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

Terms

a(0) =4a(1) =40a(2) =240a(3) =1088a(4) =4160a(5) =14208a(6) =44800a(7) =133120a(8) =377856a(9) =1034240a(10) =2748416a(11) =7127040a(12) =18104320a(13) =45187072a(14) =111083520a(15) =269484032a(16) =646184960a(17) =1533542400a(18) =3606052864a(19) =8409579520a(20) =19465764864a(21) =44753223680a(22) =102257131520a(23) =232330887168