a(n) = A059333(2^n).

Terms

a(0) =2a(1) =1a(2) =23a(3) =73a(4) =227a(5) =1669a(6) =3581a(7) =18097a(8) =19427a(9) =58537a(10) =176123a(11) =529393a(12) =2653109a(13) =36661237a(14) =33464399a(15) =43013953a(16) =597805589