a(n) = A051201(2^n).

Terms

a(0) =1a(1) =3a(2) =7a(3) =15a(4) =39a(5) =87a(6) =200a(7) =438a(8) =981a(9) =2135a(10) =4639a(11) =9971a(12) =21424a(13) =45699a(14) =97096a(15) =205563a(16) =433895a(17) =913244a(18) =1917491a(19) =4016704a(20) =8397235a(21) =17521118a(22) =36497171a(23) =75900377a(24) =157619705a(25) =326868209a(26) =676998896a(27) =1400510860a(28) =2894068715a(29) =5974185368