数字推理:1,-2,7,-20,() A4 B36 C61 D72 麻烦高手教哈,计算步骤也要,谢谢

问题描述:

数字推理:1,-2,7,-20,() A4 B36 C61 D72 麻烦高手教哈,计算步骤也要,谢谢

1 - 3^1 = -2
-2 + 3^2 = 7
7 - 3^3 = -20
-20 + 3^4 = 61