The subsequence A253066(2^n-1).

Terms

a(0) =1a(1) =6a(2) =28a(3) =112a(4) =456a(5) =1816a(6) =7288a(7) =29112a(8) =116536a(9) =465976a(10) =1864248a(11) =7456312a(12) =29826616a(13) =119303736a(14) =477220408a(15) =1908870712a(16) =7635504696a(17) =30541975096a(18) =122167987768a(19) =488671776312