A217932/2.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =14a(5) =26a(6) =52a(7) =101a(8) =201a(9) =397a(10) =794a(11) =1576a(12) =3152a(13) =6286a(14) =12568a(15) =25099a(16) =50198a(17) =100318a(18) =200636a(19) =401130a(20) =802244a(21) =1604208a(22) =3208416a(23) =6416241a(24) =12832481a(25) =25663851a(26) =51327639a(27) =102653052a(28) =205306104a(29) =410607652