diff --git a/collatz_sequence.py b/collatz_sequence.py
new file mode 100644
index 0000000..0abb828
--- /dev/null
+++ b/collatz_sequence.py
@@ -0,0 +1,29 @@
+'''
+
+Collatz Sequence
+
+1) This sequence works for every integer number;
+2) If the number is even, collatz() returns number/2. If the number is odd, collatz returns (3 * number) + 1;
+3) This program only stops when the number becomes 1.
+
+'''
+
+def collatz(number):
+    if number % 2 == 0:
+        return number // 2
+    else:
+        return (3 * number) + 1
+
+
+print("Enter a number:")
+
+try:
+    number = int(input())
+except ValueError:
+    print("Error! You must type an int number")
+    print("Enter a number:")
+    number = int(input())
+
+while number != 1:
+    number = collatz(number)
+    print(number)
\ No newline at end of file