a(n) = 16 + floor(Sum_{j=1..n-1} a(j)/2).

Terms

a(0) =16a(1) =24a(2) =36a(3) =54a(4) =81a(5) =121a(6) =182a(7) =273a(8) =409a(9) =614a(10) =921a(11) =1381a(12) =2072a(13) =3108a(14) =4662a(15) =6993a(16) =10489a(17) =15734a(18) =23601a(19) =35401a(20) =53102a(21) =79653a(22) =119479a(23) =179219a(24) =268828a(25) =403242a(26) =604863a(27) =907295a(28) =1360942a(29) =2041413