Number of rooted identity trees with 2-colored nodes.

Terms

a(0) =2a(1) =4a(2) =10a(3) =36a(4) =132a(5) =532a(6) =2222a(7) =9584a(8) =42248a(9) =189776a(10) =864830a(11) =3989656a(12) =18593424a(13) =87413444a(14) =414060796a(15) =1974260912a(16) =9467922870a(17) =45638482068a(18) =221001289714