ProjectEuler_12 -TizzyT

Module TriangularNbr 'My solution to Project Euler Problem 12
    Sub Main()
        Console.WriteLine(TriangularIndex(500))
    End Sub
    Private Function TriangularIndex(ByVal limit As UInteger) As ULong
        Dim n As ULong = 1
        Dim lnum = NbrOfDivisors(n), rnum As ULong = NbrOfDivisors(n + 1)
        While lnum * rnum < limit
            n += 1 : lnum = rnum : rnum = NbrOfDivisors(n + 1)
        End While : Return (n * (n + 1)) / 2
    End Function
    Private Function NbrOfDivisors(ByVal n As UInteger) As ULong
        Dim count = 0, p As UInteger = 3
        NbrOfDivisors = 1
        If n Mod 2 = 0 Then n /= 2
        While n Mod 2 = 0 : count += 1 : n /= 2 : End While
        NbrOfDivisors = NbrOfDivisors * (count + 1)
        While Not n = 1
            count = 0
            While n Mod p = 0 : count += 1 : n /= p : End While
            NbrOfDivisors = NbrOfDivisors * (count + 1) : p += 2
        End While
    End Function
End Module