Evil dictionary insertions in Python

gistfile1.py

from time import time

def elapsed(fn):
	t = time()
	fn()
	return time() - t

def insert_good(n):
	for i in range(2 ** n):
		d[i] = 0

def insert_evil(n):
	for i in range(2 ** n):
		d[2 ** i] = 0

d = {}
elapsed(insert_good(14)) # 0.006814002990722656

d = {}
elapsed(insert_evil(14)) # 1.0491819381713867