a(n) = 252*2^n + 140 (n>=1).

Terms

a(0) =644a(1) =1148a(2) =2156a(3) =4172a(4) =8204a(5) =16268a(6) =32396a(7) =64652a(8) =129164a(9) =258188a(10) =516236a(11) =1032332a(12) =2064524a(13) =4128908a(14) =8257676a(15) =16515212a(16) =33030284a(17) =66060428a(18) =132120716a(19) =264241292a(20) =528482444a(21) =1056964748a(22) =2113929356a(23) =4227858572a(24) =8455717004a(25) =16911433868a(26) =33822867596a(27) =67645735052a(28) =135291469964a(29) =270582939788