a(n) = 136*2^n - 112.

Terms

a(0) =24a(1) =160a(2) =432a(3) =976a(4) =2064a(5) =4240a(6) =8592a(7) =17296a(8) =34704a(9) =69520a(10) =139152a(11) =278416a(12) =556944a(13) =1114000a(14) =2228112a(15) =4456336a(16) =8912784a(17) =17825680a(18) =35651472a(19) =71303056a(20) =142606224a(21) =285212560a(22) =570425232a(23) =1140850576a(24) =2281701264a(25) =4563402640a(26) =9126805392a(27) =18253610896a(28) =36507221904a(29) =73014443920