a(n) = 2^n*F(n)*F(n+1), where F = A000045.

Terms

a(0) =0a(1) =2a(2) =8a(3) =48a(4) =240a(5) =1280a(6) =6656a(7) =34944a(8) =182784a(9) =957440a(10) =5012480a(11) =26247168a(12) =137428992a(13) =719593472a(14) =3767828480a(15) =19728629760a(16) =103300399104a(17) =540888006656