Center column a(2n,n) of A106597.

Terms

a(0) =1a(1) =3a(2) =14a(3) =72a(4) =388a(5) =2150a(6) =12134a(7) =69370a(8) =400398a(9) =2328162a(10) =13616892a(11) =80022612a(12) =472133638a(13) =2794893246a(14) =16592160944a(15) =98743919468a(16) =588913687966