' FB 1.05.0 Win64

Function factorial(n As UInteger) As UInteger
  If n = 0 Then Return 1
  Return n * factorial(n - 1)
End Function

Function catalan1(n As UInteger) As UInteger
  Dim prod As UInteger = 1
  For i As UInteger = n + 2 To 2 * n
     prod *= i
  Next
  Return prod / factorial(n)
End Function

Function catalan2(n As UInteger) As UInteger
  If n = 0 Then Return 1
  Dim sum As UInteger = 0
  For i As UInteger = 0 To n - 1
    sum += catalan2(i) * catalan2(n - 1 - i)
  Next
  Return sum
End Function

Function catalan3(n As UInteger) As UInteger
  If n = 0 Then Return 1
  Return catalan3(n - 1) * 2 * (2 * n - 1) \ (n + 1)
End Function

Print "n", "First", "Second", "Third"
Print "-", "-----", "------", "-----"
Print
For i As UInteger = 0 To 15
  Print i,  catalan1(i), catalan2(i), catalan3(i)
Next
Print
Print "Press any key to quit"
Sleep