 Why didn't the narrator provide the leprechauns with the correct equation?
Every writer must seek his own Flowery Kingdom in imagination's wide demesne, and if that search can begin and end on Earth his problem has been greatly simplified. A one-time Air Force officer, he has turned to fantasy in his lighter moments, to bring us such brightly sparkling little gems as this. But its small, mischievous pilots had a rendezvous with destiny—on Earth. Without this coefficient to give us control, we would have lacked a workable equation when we set about putting the first moon rocket around those extraordinary engines of ours, which were still in the undeveloped blueprint stage. I had to figure everything into it—diameter of the nozzle, sharpness of the edge, the velocity of approach to the point of discharge, atomic weight and structure— Oh, there is so much of this that if you're not a nuclear engineer yourself it's certain to weary you. Perhaps you had better take my word for it that without this equation—correctly stated, mind you—mankind would be well advised not to make a first trip to the moon. I smiled, and the foreman of the leprechauns—if that's what he was—saw me smile and became stiff and alert for a moment, as though suspecting that perhaps I actually could see him. Or so the legends affirmed, though I've wondered often about the truth of them. Simply because I was so lonely that my mind had become clogged.
 He believes humans need to believe in things like leprechauns in order to sustain their own race
 He knows that the leprechauns are preventing humans from destroying the Earth  He wants to take credit for the equation and is concerned they will try to get credit first  In swearing their allegiance to him, they are bound to him for eternity  He believes humans need to believe in things like leprechauns in order to sustain their own race