运行结果如下：

for i in range (4):

   for k in range(i,7-i):
       print(" * ",end="")
   print()
   for j in range(0,i+1):
       print("   ",end="")

Java版本：

import java.util.Scanner;

public class Trig {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        System.out.println("please input sign:");
        String next = scanner.next();
        triangle(next);
    }

    public static void triangle(String str) {
        //  控制循环生成几行
        for (int i = 0; i < 4; i++) {
            // 控制每行生成的个数
            for (int j = i; j < 4; j++) {
                System.out.print(str + " ");
            }
            // 为换行符号
            System.out.println("");
            // 控制下一行输出的样式 
            for (int k = 0; k <= i; k++) {
                System.out.print(" ");
            }

        }
    }
}