线性筛法+求欧拉函数

    fillchar(bz,sizeof(bz),true);        for i:=1 to maxn do phi[i]:=i;        for i:=2 to maxn do        begin                if bz[i] then                begin                        phi[i]:=i-1;                        inc(ss[0]);                        ss[ss[0]]:=i;                end;                for j:=1 to ss[0] do                begin                        if maxn/ss[j]<i then break;                        bz[i*ss[j]]:=false;                        phi[i*ss[j]]:=phi[i]*(ss[j]-1);                        if i mod ss[j]=0 then                        begin                                phi[i*ss[j]]:=phi[i]*ss[j];                                break;                        end;                end;        end;