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Task/Stern-Brocot-sequence/Sidef/stern-brocot-sequence.sidef

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+# Declare a function to generate the Stern-Brocot sequence
+func stern_brocot {
+    var list = [1, 1];
+    func {
+        list.append(list[0]+list[1], list[1]);
+        list.shift;
+    }
+}
+
+# Show the first fifteen members of the sequence.
+1..15 -> map(stern_brocot()).join(' ').say;
+
+# Show the (1-based) index of where the numbers 1-to-10 first appears
+# in the sequence, and where the number 100 first appears in the sequence.
+[(1..10)..., 100].each { |i|
+    var index = 1;
+    var generator = stern_brocot();
+    while (generator() != i) {
+        ++index;
+    }
+    say "First occurrence of #{i} is at index #{index}";
+}
+
+# Check that the greatest common divisor of all the two consecutive
+# members of the series up to the 1000th member, is always one.
+var generator = stern_brocot();
+var (a, b) = (generator(), generator());
+{
+    assert_eq(Math.gcd(a, b), 1);
+    a = b;
+    b = generator();
+} * 1000;
+
+say "All GCD's are 1";