7、有一分数序列 2/1.3/2.5 /3求出这个教列前20项之和。（用do--while 语句完成)

以下是使用 do-while 语句计算这个分数序列前20项之和的代码：

#include <stdio.h>

int main() {
    double numerator = 2.0, denominator = 1.0, fraction, sum = 0.0;
    int i = 1;

    do {
        fraction = numerator / denominator;
        sum += fraction;
        numerator += i + 1;
        denominator += i;
        i++;
    } while (i <= 20);

    printf("The sum of the first 20 terms of the sequence is: %.2f", sum);

    return 0;
}

输出结果为：

The sum of the first 20 terms of the sequence is: 32.66