Question

数列 1,4,16,64,1024…… 求2004个数除以7余几

Answer 1

1,4,16,64,256,1024,…,2²ⁿ-²,…

mod(1,7)=1

mod(4,7)=4

mod(16,7)=2

.

mod(2004,3)=0

n=2004:mod(2²ⁿ-²,7)=2