print('Going to test my knowledge here')
print('Enter a number between 1 and 20:')
numbers = []
i = 1
while 1 <= i <= 20:
    i = int(input('>> '))
print('Ok adding %d to numbers set: ' % i)
numbers.append(i)
print('Okay the numbers set is now: ', numbers)
How to use raw_input() with while-loop