local fn Chowla( n as NSUInteger ) as NSUInteger
  NSUInteger i, j, r = 0

  i = 2
  while ( i * i <= n )
    j = n / i
    if ( n mod i == 0 )
      r += i
      if ( i != j )
        r += j
      end if
    end if
    i++
  wend
end fn = r

local fn DoIt
  NSUInteger n, count = 0, power = 100, limit, k, kk, p = 0

  for n = 1 to 37
    printf @"chowla(%u) = %u", n, fn Chowla( n )
  next

  for n = 2 to 10000000
    if ( fn Chowla(n) == 0 ) then count ++
    if ( n mod power == 0  ) then printf @"There are %u primes < %-7u", count, power : power *= 10
  next

  count = 0
  limit = 350000000
  k = 2 : kk = 3
  do
    p = k * kk
    if ( fn Chowla( p ) == p - 1 )
      printf @"%9u is a perfect number", p
      count++
    end if
    k = kk + 1
    kk = kk + k
  until ( p > limit )
  printf @"There are %u perfect numbers < %u", count, limit
end fn

fn DoIt

HandleEvents