数列问题的考查形式多样,成为高考试题的一道亮丽的风景线.结合数阵进行考查就是其中一种令人耳目一新的形式.例1数列1,2,…,n(n∈*N)是一个以1为首项、1为公差的等差数列,其通项公式an=n,前n项和Sn=(1+n)n/2.若将该数列排成如图1的三角形数阵的形式,则根据排列规律,数阵中的第k(k≥3)行 The sequence of exam questions in various forms, as the entrance exam questions a beautiful landscape. Combining the array to examine is one of a refreshing form. Example 1 The sequence of 1,2, ..., n (n ∈ * N) is a 1 is the first item, 1 is the tolerance of the arithmetic sequence, the general formula an = n, the first n and Sn = (1 + n) n / 2. If the number of rows arranged in Figure 1 triangular array form , According to the arrangement rule, the kth (k≥3) rows in the array