diff --git a/21/main.py b/21/main.py
new file mode 100644
index 0000000..90ea883
--- /dev/null
+++ b/21/main.py
@@ -0,0 +1,47 @@
+import os
+import math
+import numpy as np
+
+# Evaluate the sum all amicable numbers under 10000
+# A pair of number is amicable if the sum of their proper divisors is equal
+# to each other, they are then both called amicable numbers
+
+def getDivs(n):
+	ds = [True] * math.ceil(n/2)
+
+	for i in range(1, len(ds)):
+		if ds[i] and n % (i+1) != 0:
+			j = i
+			while j < len(ds):
+				ds[j] = False
+				j = j + i + 1
+
+	res = []
+	for i in range(0, len(ds)):
+		if ds[i]:
+			res.append(i+1)
+	return res
+
+def getSumDivs(n):
+	return sum(getDivs(n))
+
+def main():
+	print("Hello, this is Patrick")
+
+	dsums = [getSumDivs(x) for x in range(1, 10001)]
+
+	res = 0
+	for i in range(len(dsums)):
+		di = dsums[i]
+		if (i+1) != di:
+			if di-1 < len(dsums):
+				if i+1 == dsums[di-1]:
+					res = res + i + 1
+			else:
+				dj = getSumDivs(di)
+				if i+1 == dj:
+					res = res + i + 1
+	print(res)
+
+if __name__ == "__main__":
+	main()
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