include "NSLog.incl"

NSInteger local fn GCD( a as NSInteger, b as NSInteger )
  if ( a == 0 ) then return b
  return fn GCD( b % a, a )
end fn = 0

void local fn CalcYellowstoneSequence( terms as int )
  CFMutableArrayRef sequence = fn MutableArrayWithObjects( @1, @2, @3, NULL )

  for int n = 3 to terms - 1
    NSInteger prev1 = fn NumberIntegerValue( fn ArrayObjectAtIndex( sequence, n - 1 ) )
    NSInteger prev2 = fn NumberIntegerValue( fn ArrayObjectAtIndex( sequence, n - 2 ) )
    NSInteger candidate = 1

    while (YES)
      if ( !fn ArrayContainsObject( sequence, @(candidate) ) && fn GCD( candidate, prev1 ) == 1 && fn GCD( candidate, prev2 ) > 1 )
        MutableArrayAddObject( sequence, @(candidate) )
        break
      end if
      candidate++
    wend
  next

  NSLog( @"Yellowstone sequence up to %d terms:", terms )
  for CFNumberRef num in sequence
    NSLog( @"%@ \b", num )
  next
end fn

fn CalcYellowstoneSequence( 30 )

HandleEvents