2^1 ==> 2 n=02^2 ==> 4 n=12^3 ==> 8 n=22^4 ==> 6 n=32^5 ==> 2 n=42^6 ==> 4 n=5尾数循环当n=4k时,2^n+1的末尾数字为2,当n=4k+1时,2^n+1的末尾数字为4,当n=4k+2时,2^n+1的末尾数字为8,当n=4k+3时,2^n+1的末尾数字...