gistfile1.txt

In [5]: [ (n, 0.5 ** n) for n in range(1, 15) ]                                                                                              
Out[5]: 
[(1, 0.5),
 (2, 0.25),
 (3, 0.125),
 (4, 0.0625),
 (5, 0.03125),
 (6, 0.015625),
 (7, 0.0078125),
 (8, 0.00390625),
 (9, 0.001953125),
 (10, 0.0009765625),
 (11, 0.00048828125),
 (12, 0.000244140625),
 (13, 0.0001220703125),
 (14, 6.103515625e-05)]