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;