Number of rooted trees with 3-colored nodes.

Terms

a(0) =3a(1) =9a(2) =45a(3) =246a(4) =1485a(5) =9432a(6) =62625a(7) =428319a(8) =3000393a(9) =21410436a(10) =155106693a(11) =1137703869a(12) =8432624850a(13) =63060142671a(14) =475196487363