a(n) = n*4^(n-1).

Terms

a(0) =0a(1) =1a(2) =8a(3) =48a(4) =256a(5) =1280a(6) =6144a(7) =28672a(8) =131072a(9) =589824a(10) =2621440a(11) =11534336a(12) =50331648a(13) =218103808a(14) =939524096a(15) =4026531840a(16) =17179869184a(17) =73014444032a(18) =309237645312