试题与答案

已知数列{an}满足a1=1,且对任意的正整数n有an+3≥an+3,an+1≤

题型:解答题

题目:

已知数列{an}满足a1=1,且对任意的正整数n有an+3≥an+3,an+1≤an+1成立.
(1)求数列{an}的通项公式;
(2)若数列{an},{bn}满足an=
b1+2b 2+3b3+…+nbn
1+2+3+…+n
,求证:数列{bn}是等差数列;
(3)若数列{cn},{dn}满足dn=
c1+2c 2+3c3+…+ncn
1+2+3+…+n
,求证:数列{cn}成等差数列的充要条件是数列{dn}等差数列.

答案:

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参考答案:C

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