Public NotInheritable Class CombinationComparer : Implements IEqualityComparer(Of String)
 
        Public Shadows Function Equals(ByVal x As String, ByVal y As String) As Boolean _
        Implements IEqualityComparer(Of String).Equals
 
            ' (temporalmente) Ordeno de forma ascendente los números de una cadena de texto delimitada por comas;
            '
            ' e.g.:
            ' Una cadena de texto como "3, 1, 2" (con, o sin espacios en blanco), 
            ' se transformaría en "1,2,3" (sin espacios en blanco).
 
            x = String.Join(",", From value As String In x.Split({","c, " "c}, StringSplitOptions.RemoveEmptyEntries)
                                 Order By value Ascending)
 
            y = String.Join(",", From value As String In y.Split({","c, " "c}, StringSplitOptions.RemoveEmptyEntries)
                                 Order By value Ascending)
 
            #If DEBUG Then
                        Console.WriteLine(String.Format("x:{0}", x))
                        Console.WriteLine(String.Format("y:{0}", y))
                        Console.WriteLine()
            #End If
 
            Return (x = y)
 
        End Function
 
        Public Shadows Function GetHashCode(ByVal obj As String) As Integer _
        Implements IEqualityComparer(Of String).GetHashCode
 
            Return MyBase.GetHashCode()
 
        End Function
 
    End Class

Dim items As String() = Me.ListBox1.Items.Cast(Of String)().ToArray()
items = items.Distinct(New CombinationComparer).ToArray()
 
With Me.ListBox1
    .SuspendLayout()
    .Items.Clear()
    .Items.AddRange(items)
    .ResumeLayout()
End With
 

        Dim Elementos As IEnumerable(Of Integer) = {2, 6, 10, 11, 17, 20, 24, 34, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 50}
        Dim EleX As Integer = 0
        Dim EleX2 As Integer = 0
        ListBox1.Items.Clear() 'Limpia el ListBox
        For I1 As Integer = 0 To Elementos.Count - 1 : EleX += 1
            For I2 As Integer = EleX To Elementos.Count - 1
                For I3 As Integer = EleX To Elementos.Count - 1
                    If Elementos(I2) <> Elementos(I3) And Elementos(I3) > Elementos(I2) Then
                        ListBox1.Items.Add(String.Format("{0:00}, {1:00}, {2:00}", Elementos(I1), Elementos(I2), Elementos(I3)))
                    End If
 
                Next
            Next
        Next
        MessageBox.Show("Combinaciones: " & ListBox1.Items.Count)

        Dim Elementos As IEnumerable(Of Integer) = {20, 24, 34, 44, 45}
        Dim EleX As Integer = 0
        Dim EleX2 As Integer = 0
        ListBox1.Items.Clear() 'Limpia el ListBox
        For I1 As Integer = 0 To Elementos.Count - 1 : EleX += 1
            For I2 As Integer = EleX To Elementos.Count - 1
                For I3 As Integer = EleX To Elementos.Count - 1
                    If Elementos(I2) <> Elementos(I3) And Elementos(I3) > Elementos(I2) Then
                        ListBox1.Items.Add(String.Format("{0:00}, {1:00}, {2:00}", Elementos(I1), Elementos(I2), Elementos(I3)))
                    End If
 
                Next
            Next
        Next
        MessageBox.Show("Combinaciones: " & ListBox1.Items.Count)