将1-2001的数字分为:3n-1,3n和3n+1共3类,1)3n-1类3n-1=(4-1)n-1=4n-(n+1)当n+1为4的倍数时,3n-1为4的倍数,n+1=4mn=4m-13n-1=3(4m-1)-1=12m-41≤12m-4≤20015≤12m≤20051≤m≤167共167个2)3n形,3n=4n-n此时n=4m时为4的倍数1≤12m≤20011≤m≤166有166个3)3n+1类3n+1=(4-1)n+1=4n-(n-1)当n-1为4的倍数时,3n+1为4的倍数,n-1=4mn=4m+13n+1=3(4m+1)+1=12m+41≤12m+4≤2001...
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