a(0) = 19; for n>0, successively subtract 5, subtract 3 and double.

Terms

a(0) =19a(1) =14a(2) =11a(3) =22a(4) =17a(5) =14a(6) =28a(7) =23a(8) =20a(9) =40a(10) =35a(11) =32a(12) =64a(13) =59a(14) =56a(15) =112a(16) =107a(17) =104a(18) =208a(19) =203a(20) =200a(21) =400a(22) =395a(23) =392a(24) =784a(25) =779a(26) =776a(27) =1552a(28) =1547a(29) =1544