Even bisection of A173610.

Terms

a(0) =1a(1) =2a(2) =10a(3) =60a(4) =384a(5) =2752a(6) =19436a(7) =132888a(8) =938448a(9) =6977712a(10) =52748180a(11) =402295360a(12) =3045774336a(13) =22798000896a(14) =169191995264