2n乘以2的2n次方的前n
2n乘2n等于
2n乘以2n等于
2的n次方乘以2n减一1
2n与2的n次方的
2n乘以n
2的2n次方减2的n次方怎
2的2n次方等于4的n次
2n次方减2n减1
2N乘N等于
