a(n) = 14 + floor( (1 + Sum_{j=0..n-1} a(j)) / 2).

Terms

a(0) =14a(1) =21a(2) =32a(3) =48a(4) =72a(5) =108a(6) =162a(7) =243a(8) =364a(9) =546a(10) =819a(11) =1229a(12) =1843a(13) =2765a(14) =4147a(15) =6221a(16) =9331a(17) =13997a(18) =20995a(19) =31493a(20) =47239a(21) =70859a(22) =106288a(23) =159432a(24) =239148a(25) =358722a(26) =538083a(27) =807125a(28) =1210687a(29) =1816031