diff --git a/tools/__init__.py b/tools/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/aoc.py b/tools/aoc.py
similarity index 98%
rename from aoc.py
rename to tools/aoc.py
index b7236ca..7e21a9c 100644
--- a/aoc.py
+++ b/tools/aoc.py
@@ -1,8 +1,8 @@
 import os
-import tools
 from typing import List, Any, Type, Union
+from .tools import get_script_dir
 
-BASE_PATH = tools.get_script_dir()
+BASE_PATH = get_script_dir()
 INPUTS_PATH = os.path.join(BASE_PATH, 'inputs')
 
 
diff --git a/coordinate.py b/tools/coordinate.py
similarity index 100%
rename from coordinate.py
rename to tools/coordinate.py
diff --git a/daemon.py b/tools/daemon.py
similarity index 100%
rename from daemon.py
rename to tools/daemon.py
diff --git a/datafiles.py b/tools/datafiles.py
similarity index 100%
rename from datafiles.py
rename to tools/datafiles.py
diff --git a/grid.py b/tools/grid.py
similarity index 100%
rename from grid.py
rename to tools/grid.py
diff --git a/tools/int_seq.py b/tools/int_seq.py
new file mode 100644
index 0000000..67dbd96
--- /dev/null
+++ b/tools/int_seq.py
@@ -0,0 +1,5 @@
+def triangular(n: int) -> int:
+    """
+    0, 1, 3, 6, 10, 15, ...
+    """
+    return int(n * (n + 1) / 2)
diff --git a/irc.py b/tools/irc.py
similarity index 100%
rename from irc.py
rename to tools/irc.py
diff --git a/schedule.py b/tools/schedule.py
similarity index 100%
rename from schedule.py
rename to tools/schedule.py
diff --git a/setup.py b/tools/setup.py
similarity index 100%
rename from setup.py
rename to tools/setup.py
diff --git a/simplesocket.py b/tools/simplesocket.py
similarity index 100%
rename from simplesocket.py
rename to tools/simplesocket.py
diff --git a/tools.py b/tools/tools.py
similarity index 100%
rename from tools.py
rename to tools/tools.py