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

Terms

a(0) =0a(1) =1a(2) =6a(3) =21a(4) =60a(5) =155a(6) =378a(7) =889a(8) =2040a(9) =4599a(10) =10230a(11) =22517a(12) =49140a(13) =106483a(14) =229362a(15) =491505a(16) =1048560a(17) =2228207a(18) =4718574a(19) =9961453a(20) =20971500a(21) =44040171a(22) =92274666a(23) =192937961a(24) =402653160a(25) =838860775a(26) =1744830438a(27) =3623878629a(28) =7516192740a(29) =15569256419