Number of red-black rooted trees with n-1 internal nodes.

Terms

a(0) =0a(1) =1a(2) =2a(3) =2a(4) =3a(5) =8a(6) =14a(7) =20a(8) =35a(9) =64a(10) =122a(11) =260a(12) =586a(13) =1296a(14) =2708a(15) =5400a(16) =10468a(17) =19888a(18) =37580a(19) =71960a(20) =140612a(21) =279264a(22) =560544a(23) =1133760a(24) =2310316a(25) =4750368a(26) =9876264a(27) =20788880a(28) =44282696a(29) =95241664