a(n) = A299914(2n).

Terms

a(0) =0a(1) =1a(2) =9a(3) =69a(4) =513a(5) =3789a(6) =27945a(7) =206037a(8) =1518993a(9) =11198493a(10) =82558521a(11) =608644773a(12) =4487100705a(13) =33080169069a(14) =243876313161