Number of n-node rooted trees with nodes of 2 colors.

Terms

a(0) =2a(1) =4a(2) =14a(3) =52a(4) =214a(5) =916a(6) =4116a(7) =18996a(8) =89894a(9) =433196a(10) =2119904a(11) =10503612a(12) =52594476a(13) =265713532a(14) =1352796790a(15) =6933598208a(16) =35747017596a(17) =185260197772a(18) =964585369012