金字塔/99乘法表

fo = open('c.txt','a')
for i in range(1,20,2):
    str = ('*'*i).center(19)
    fo.write(str)
    fo.write('\n')

f = open('c.txt','w')
s = ''
for i in range(1,10):
    for j in range(1,i+1):
        s +=('{}*{}={} '.format(j,i,i*j))
    s += '\n'
f.write(s)