Elements to the right of the central elements of the even-Pascal triangle A028326.

Terms

a(0) =2a(1) =2a(2) =6a(3) =2a(4) =8a(5) =2a(6) =20a(7) =10a(8) =2a(9) =30a(10) =12a(11) =2a(12) =70a(13) =42a(14) =14a(15) =2a(16) =112a(17) =56a(18) =16a(19) =2a(20) =252a(21) =168a(22) =72a(23) =18a(24) =2a(25) =420a(26) =240a(27) =90a(28) =20a(29) =2