a(n) = 136*2^n - 78 (n>=0).

Terms

a(0) =58a(1) =194a(2) =466a(3) =1010a(4) =2098a(5) =4274a(6) =8626a(7) =17330a(8) =34738a(9) =69554a(10) =139186a(11) =278450a(12) =556978a(13) =1114034a(14) =2228146a(15) =4456370a(16) =8912818a(17) =17825714a(18) =35651506a(19) =71303090a(20) =142606258a(21) =285212594a(22) =570425266a(23) =1140850610a(24) =2281701298a(25) =4563402674a(26) =9126805426a(27) =18253610930a(28) =36507221938a(29) =73014443954