Start lucus prime test algo

lucas.py

@@ -0,0 +1,24 @@
+# Finding lucas pseudoprimes
+from math import sqrt
+
+def isqrt(n):
+    """ Find the integer square root of n via newton's method, code via
+    stackoverflow:
+
+    (https://stackoverflow.com/questions/15390807/integer-square-root-in-python)
+    """
+    x = n
+    y = (x + 1) // 2
+    while y < x:
+        x = y
+        y = (x + n // x) // 2
+    return x
+
+def hasIntSQRT(n):
+    """Detect whether the square root of n is an integer,
+    i.e. whether the isqrt(n) is the true square root.
+    """
+    isq = isqrt(n)
+    return isq * isq == n
+
+