(A192469)/2.

Terms

a(0) =1a(1) =4a(2) =22a(3) =112a(4) =589a(5) =3100a(6) =16393a(7) =86800a(8) =459994a(9) =2438536a(10) =12929377a(11) =68557720a(12) =363537265a(13) =1927735708a(14) =10222301758a(15) =54206461120a(16) =287444443765