Data commit

Task/Chernicks-Carmichael-numbers/FreeBASIC/chernicks-carmichael-numbers.basic

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+#include "isprime.bas"
+
+Function PrimalityPretest(k As Integer) As Boolean
+    Dim As Integer ppp(1 To 8) = {3,5,7,11,13,17,19,23}
+    For i As Integer = 1 To Ubound(ppp)
+        If k Mod ppp(i) = 0 Then Return (k <= 23)
+    Next i
+    Return True
+End Function
+
+Function isChernick(n As Integer, m As Integer) As Boolean
+    Dim As Integer i, t = 9 * m
+
+    If Not PrimalityPretest(6 * m + 1) Then Return False
+    If Not PrimalityPretest(12 * m + 1) Then Return False
+
+    For i = 1 To n-1
+        If Not PrimalityPretest(t * (2 ^ i) + 1) Then Return False
+    Next i
+
+    If Not isPrime(6 * m + 1) Then Return False
+    If Not isPrime(12 * m + 1) Then Return False
+
+    For i = 1 To n - 2
+        If Not isPrime(t * (2 ^ i) + 1) Then Return False
+    Next i
+    Return True
+End Function
+
+Dim As Uinteger multiplier, k, m = 1
+For n As Integer = 3 To 9
+    multiplier = Iif (n > 4, 2 ^ (n-4), 1)
+    If n > 5 Then multiplier *= 5
+
+    k = 1
+    Do
+        m = k * multiplier
+        If isChernick(n, m) Then
+            Print "a(" & n & ") has m = " & m
+            Exit Do
+        End If
+        k += 1
+    Loop
+Next n
+Sleep