数列1,2,3,4,1,2,3,4……的通项公式是什么?好像挺难的_数学解答

数列1,2,3,4,1,2,3,4……的通项公式是什么?
好像挺难的

人气：351 ℃　时间：2020-03-22 02:15:00

解答

An=2.5-SIN((2n-1)/4)×(COS((2n-1)/4)+2^0.5)由SIN((2n-1)/4)得出(1/2)^0.5,(1/2)^0.5,-(1/2)^0.5,-(1/2)^0.5由COS((2n-1)/4)+2^0.5得出3/2×2^0.5,1/2×2^0.5,1/2×2^0.5,3/2×2^0.5相乘得1.5,0.5,-0.5,-1.5用2.5...