Problem 124 easy with existing prime factors function.

python/e124.py

@@ -0,0 +1,24 @@
+from lib_prime import prime_factors
+
+
+def radical(n: int) -> int:
+    fs = prime_factors(n)
+    r = 1
+    for f in set(fs):
+        r *= f
+    return r
+
+
+def euler_124():
+    assert radical(504) == 42
+    xs = []
+    for n in range(1, 100001):
+        xs.append((radical(n), n))
+    xs = sorted(xs)
+    return xs[10000 - 1][1]
+
+
+if __name__ == "__main__":
+    solution = euler_124()
+    print("e124.py: " + str(solution))
+    assert(solution == 21417)