Lucas 8-step numbers.

Terms

a(0) =1a(1) =3a(2) =7a(3) =15a(4) =31a(5) =63a(6) =127a(7) =255a(8) =502a(9) =1003a(10) =2003a(11) =3999a(12) =7983a(13) =15935a(14) =31807a(15) =63487a(16) =126719a(17) =252936a(18) =504869a(19) =1007735a(20) =2011471a(21) =4014959a(22) =8013983a(23) =15996159a(24) =31928831a(25) =63730943a(26) =127208950a(27) =253913031a(28) =506818327a(29) =1011625183