The subsequence A247649(2^n-1).

Terms

a(0) =1a(1) =5a(2) =7a(3) =19a(4) =25a(5) =77a(6) =103a(7) =307a(8) =409a(9) =1229a(10) =1639a(11) =4915a(12) =6553a(13) =19661a(14) =26215a(15) =78643a(16) =104857a(17) =314573a(18) =419431a(19) =1258291a(20) =1677721a(21) =5033165a(22) =6710887a(23) =20132659a(24) =26843545a(25) =80530637a(26) =107374183a(27) =322122547a(28) =429496729a(29) =1288490189