Even numbers to the left of the central elements of the (2,1)-Pascal triangle A029653.

Terms

a(0) =2a(1) =2a(2) =2a(3) =2a(4) =2a(5) =16a(6) =2a(7) =2a(8) =36a(9) =2a(10) =2a(11) =64a(12) =140a(13) =196a(14) =2a(15) =204a(16) =336a(17) =2a(18) =100a(19) =540a(20) =714a(21) =2a(22) =1254a(23) =2a(24) =144a(25) =506a(26) =1210a(27) =2640a(28) =2a(29) =650