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

Terms

a(0) =1a(1) =3a(2) =8a(3) =20a(4) =48a(5) =112a(6) =256a(7) =576a(8) =1280a(9) =2816a(10) =6144a(11) =13312a(12) =28672a(13) =61440a(14) =131072a(15) =278528a(16) =589824a(17) =1245184a(18) =2621440a(19) =5505024a(20) =11534336a(21) =24117248a(22) =50331648a(23) =104857600a(24) =218103808a(25) =452984832a(26) =939524096a(27) =1946157056a(28) =4026531840a(29) =8321499136