a(n) = A070952(2^n).

Terms

a(0) =3a(1) =3a(2) =4a(3) =7a(4) =15a(5) =26a(6) =64a(7) =132a(8) =253a(9) =498a(10) =1033a(11) =2027a(12) =4089a(13) =8141a(14) =16416a(15) =32715a(16) =65722a(17) =131374a(18) =262159a(19) =524211a(20) =1048630a(21) =2097291a(22) =4195039a(23) =8387885