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

Terms

a(0) =0a(1) =0a(2) =2a(3) =18a(4) =112a(5) =600a(6) =2976a(7) =14112a(8) =65024a(9) =293760a(10) =1308160a(11) =5761536a(12) =25153536a(13) =109025280a(14) =469704704a(15) =2013143040a(16) =8589672448a(17) =36506664960a(18) =154617643008a(19) =652832538624