first_list = ...

newlist = []
for item in first_list:
    newitem = ...
    newlist.append(newitem)

[2**x for x in range(16)]

[1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768]

import pprint

first_list = range(16)

newlist = []
for item in first_list:
    newitem = 2**item
    newlist.append(newitem)
    
pprint.pprint(newlist)

[1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768]

first_list = ...

newlist = []
for item in first_list:
    if ... :
        newitem = ...
        newlist.append(newitem)
    