Imports System
Module PrimeFibonacci
Function IsPrime(n As ULong) As Boolean
If n < 2 Then Return False
If n = 2 OrElse n = 3 Then Return True
If n Mod 2 = 0 Then Return False
Dim i As ULong = 3
While i * i <= n
If n Mod i = 0 Then Return False
i += 2
End While
Return True
End Function
Function NextFib(state As ULong()) As ULong
Dim f As ULong = state(0)
Dim nextVal As ULong = state(0) + state(1)
state(0) = state(1)
state(1) = nextVal
Return f
End Function
Sub Main()
Dim fibState As ULong() = {1UL, 1UL}
Dim count As Integer = 0
While count < 10
Dim f As ULong = NextFib(fibState)
If IsPrime(f) Then
Console.Write(f & " ")
count += 1
End If
End While
End Sub
End Module
' run:
'
' 2 3 5 13 89 233 1597 28657 514229 433494437
'
