get "libhdr"

let totient(n) = valof
$(  let tot = n and i = 2
    while i*i <= n
    $(  if n rem i = 0
        $(  while n rem i = 0 do n := n / i
            tot := tot - tot/i
        $)
        if i=2 then i:=1
        i := i+2
    $)
    resultis n>1 -> tot-tot/n, tot
$)

let start() be
$(  let count = 0
    writes(" N  Totient  Prime*N")
    for n = 1 to 25
    $(  let tot = totient(n)
        let prime = n-1 = tot
        if prime then count := count + 1
        writef("%I2  %I7  %S*N", n, tot, prime -> "  Yes", "   No")
    $)
    writef("Number of primes up to %I6: %I4*N", 25, count)
    for n = 26 to 10000
    $(  if totient(n) = n-1 then count := count + 1
        if n = 100 | n = 1000 | n = 10000 then
            writef("Number of primes up to %I6: %I4*N", n, count)
    $)
$)