Number of reduced tree pairs of n-carets.

Terms

a(0) =0a(1) =1a(2) =2a(3) =14a(4) =108a(5) =930a(6) =8700a(7) =86598a(8) =904176a(9) =9804516a(10) =109624536a(11) =1257136130a(12) =14726063264a(13) =175650153588