From 8fe553d7e4825940c24af045fcc51e1eaa2ac8c2 Mon Sep 17 00:00:00 2001
From: Sanders Lin <45224617+SandersLin@users.noreply.github.com>
Date: Thu, 6 Dec 2018 19:06:26 +0800
Subject: [PATCH 1/3] Create  collatz_sequence.py

---
 collatz_sequence.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 collatz_sequence.py

diff --git a/collatz_sequence.py b/collatz_sequence.py
new file mode 100644
index 000000000000..7578e6b59ed8
--- /dev/null
+++ b/collatz_sequence.py
@@ -0,0 +1,25 @@
+def collatz_sequence(n):
+  """Collatz conjecture: start with any positive integer n.Next termis obtained from the previous term as follows: 
+  if the previous term is even, the next term is one half the previous term. 
+  If the previous term is odd, the next term is 3 times the previous term plus 1. 
+  The conjecture states the sequence will always reach 1 regaardess of starting n."""
+  sequence = [n]
+  while n != 1:
+    if n % 2 == 0:# even
+      n //= 2 
+    else:
+      n = 3*n +1
+    sequence.append(n)
+  return sequence
+
+
+def main():
+  n = 43
+  sequence = collatz_sequence(n)
+  print(sequence)
+  print("collatz sequence from %d took %d steps."%(n,len(sequence)))
+
+
+
+if __name__ == '__main__':
+  main()

From 838c7c98c551c9c45a17d1aac131869950c92c50 Mon Sep 17 00:00:00 2001
From: John Law <johnlaw.po@gmail.com>
Date: Wed, 31 Jul 2019 23:04:34 +0800
Subject: [PATCH 2/3] Update and rename collatz_sequence.py to
 maths/collatz_sequence.py

---
 collatz_sequence.py       | 25 -------------------------
 maths/collatz_sequence.py | 25 +++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 25 deletions(-)
 delete mode 100644 collatz_sequence.py
 create mode 100644 maths/collatz_sequence.py

diff --git a/collatz_sequence.py b/collatz_sequence.py
deleted file mode 100644
index 7578e6b59ed8..000000000000
--- a/collatz_sequence.py
+++ /dev/null
@@ -1,25 +0,0 @@
-def collatz_sequence(n):
-  """Collatz conjecture: start with any positive integer n.Next termis obtained from the previous term as follows: 
-  if the previous term is even, the next term is one half the previous term. 
-  If the previous term is odd, the next term is 3 times the previous term plus 1. 
-  The conjecture states the sequence will always reach 1 regaardess of starting n."""
-  sequence = [n]
-  while n != 1:
-    if n % 2 == 0:# even
-      n //= 2 
-    else:
-      n = 3*n +1
-    sequence.append(n)
-  return sequence
-
-
-def main():
-  n = 43
-  sequence = collatz_sequence(n)
-  print(sequence)
-  print("collatz sequence from %d took %d steps."%(n,len(sequence)))
-
-
-
-if __name__ == '__main__':
-  main()
diff --git a/maths/collatz_sequence.py b/maths/collatz_sequence.py
new file mode 100644
index 000000000000..49b2345ceafd
--- /dev/null
+++ b/maths/collatz_sequence.py
@@ -0,0 +1,25 @@
+def collatz_sequence(n):
+    """
+    Collatz conjecture: start with any positive integer n.Next termis obtained from the previous term as follows: 
+    if the previous term is even, the next term is one half the previous term. 
+    If the previous term is odd, the next term is 3 times the previous term plus 1. 
+    The conjecture states the sequence will always reach 1 regaardess of starting n.
+    """
+    sequence = [n]
+    while n != 1:
+        if n % 2 == 0:# even
+            n //= 2 
+        else:
+            n = 3*n +1
+        sequence.append(n)
+    return sequence
+
+
+def main():
+    n = 43
+    sequence = collatz_sequence(n)
+    print(sequence)
+    print("collatz sequence from %d took %d steps."%(n,len(sequence)))
+
+if __name__ == '__main__':
+    main()

From 38d459cb1eba49e2c8c8dd4bf5c68388d962e483 Mon Sep 17 00:00:00 2001
From: John Law <johnlaw.po@gmail.com>
Date: Wed, 31 Jul 2019 23:09:03 +0800
Subject: [PATCH 3/3] doctest

---
 maths/collatz_sequence.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/maths/collatz_sequence.py b/maths/collatz_sequence.py
index 49b2345ceafd..9f88453d518b 100644
--- a/maths/collatz_sequence.py
+++ b/maths/collatz_sequence.py
@@ -4,6 +4,9 @@ def collatz_sequence(n):
     if the previous term is even, the next term is one half the previous term. 
     If the previous term is odd, the next term is 3 times the previous term plus 1. 
     The conjecture states the sequence will always reach 1 regaardess of starting n.
+    Example:
+    >>> collatz_sequence(43)
+    [43, 130, 65, 196, 98, 49, 148, 74, 37, 112, 56, 28, 14, 7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1]
     """
     sequence = [n]
     while n != 1: