table(+, +, nt)
phi(X, 0, _) = X.
phi(X, A, Primes) = phi(X, A - 1, Primes) - phi(X // Primes[A], A - 1, Primes).

pi(N) = Count, N < 2 => Count = 0.
pi(N) = Count =>
    M = floor(sqrt(N)),
    A = pi(M),
    Count = phi(N, A, math.primes(M)) + A - 1.

main =>
    N = 1,
    foreach (K in 0..9)
        writef("10^%w    %w%n", K, pi(N)),
        N := N * 10.