RosettaCodeData/Task/Catalan-numbers/FreeBASIC/catalan-numbers.basic

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' 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