a(n) = A007504(A134126(n)).

Terms

a(0) =2a(1) =5a(2) =17a(3) =58a(4) =129a(5) =5117a(6) =43201a(7) =329401a(8) =1459228a(9) =111461983a(10) =269553485a(11) =316504138a(12) =734845192a(13) =6185946407a(14) =10731178047a(15) =22691403557a(16) =148086969623a(17) =474635764987