for 循环

for i in range(1,8,2):

    if i<7:
        str1='*'*i
        print(f'{str1:^5}')
    else:
        str1 = '*'
        print(f'{str1:^5}')
结果
  *  
 *** 
*****
  *  

    for i in range(1,5):
        for j in range(5):
            if i > j:
                print("*",end='')
        print(" ")

结果
* 
** 
*** 
****