Dirichlet g.f.: Product_{k>=2} 1 / (1 - k^(-s))^(2^(k - 1)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =16a(5) =40a(6) =64a(7) =148a(8) =266a(9) =544a(10) =1024a(11) =2156a(12) =4096a(13) =8320a(14) =16448a(15) =33089a(16) =65536a(17) =131732a(18) =262144a(19) =525488a(20) =1048832a(21) =2099200a(22) =4194304a(23) =8393648a(24) =16777352a(25) =33562624a(26) =67109908a(27) =134234816a(28) =268435456a(29) =536906368