Added section for number theoretic functions

imp/math/numbers.py

@@ -0,0 +1,16 @@
+from imp.math.primefac import factors
+
+def divisors(n: int) -> int:
+    '''
+    Returns the proper divisors of an integer n.
+    Also called the "aliquot parts" of n. 
+    '''
+    pf = factors(n)
+    for (prime, multiplicity) in pf:
+    
+
+def aliquots(n: int) -> int:
+    return proper_divisors(n)
+
+def amicable(n: int) -> int:
+    sum(proper_divisors())

imp/math/util.py

@@ -1,2 +1,8 @@
+from itertools import chain, combinations
+
 def digits(n: int) -> int:
     return len(str(n))
+
+def powerset(iterable):
+    s = list(iterable)
+    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))