数列历来是高考的热点问题,涉及的知识点多,题型多变,解题的思想和方法多种多样.在各类考试中,经常遇到与项的奇偶性有关的数列问题,下面通过举例,探讨此类问题的解法.例1已知数列{a_n}满足a_(n+2)=a_n+2(n∈N*)且a_1=1,a_2=4.(1)求数列{a_n}的通项公式a_n.(2)求数列{a_n}的前n项和S_n. The series has always been a hot issue of the college entrance examination, involving more knowledge, variety of questions, ideas and methods of solving a variety of questions in various exams, often encountered with the parity of items related to the sequence of questions, the following through For example, we discuss the solution of this kind of problem.Example 1 It is known that the sequence {a_n} satisfies a_ (n + 2) = a_n + 2 (n∈N *) and a_1 = 1 and a_2 = 4. (1) } The general term of the formula a_n. (2) Find the first n items of columns {a_n} and S_n.