a(n) = 144*2^n - 20 (n>=1).

Terms

a(0) =268a(1) =556a(2) =1132a(3) =2284a(4) =4588a(5) =9196a(6) =18412a(7) =36844a(8) =73708a(9) =147436a(10) =294892a(11) =589804a(12) =1179628a(13) =2359276a(14) =4718572a(15) =9437164a(16) =18874348a(17) =37748716a(18) =75497452a(19) =150994924a(20) =301989868a(21) =603979756a(22) =1207959532a(23) =2415919084a(24) =4831838188a(25) =9663676396a(26) =19327352812a(27) =38654705644a(28) =77309411308