a(n) = A212205(2*n + 1).

Terms

a(0) =1a(1) =4a(2) =18a(3) =86a(4) =426a(5) =2162a(6) =11166a(7) =58438a(8) =309042a(9) =1648154a(10) =8851206a(11) =47813790a(12) =259585002a(13) =1415431266a(14) =7747200558a(15) =42545600310a(16) =234346445154