with javascript_semantics
atom t0 = time()
constant maxphi = 1e7
sequence s_phi
procedure computePhi()
    s_phi = tagset(maxphi)
    for i=2 to maxphi do
        if s_phi[i]=i then
            for j=i to maxphi by i do
                s_phi[j] -= s_phi[j] / i;
            end for
        end if
    end for
end procedure

function countPrimes(int lo, hi)
    int count = 0;
    for i=lo to hi do
        if s_phi[i] == i-1 then
            count += 1
        end if
    end for
    return count;
end function

computePhi()
printf(1," n  phi   prime\n")
printf(1," --------------\n")
for n=1 to 25 do
    integer tot = s_phi[n]
    bool prime = (n-1=tot)
    printf(1,"%2d   %2d   %t\n",{n,tot,prime})
end for
printf(1,"\n")
for n in {25,1e2,1e3,1e4,1e5,1e6,1e7} do
    printf(1,"Number of primes up to %d = %d\n",{n,countPrimes(1,n)})
end for
?elapsed(time()-t0)