Lots of readers know the A.E. van Vogt story that Sir Arthur C. Clarke
referred to ** IN ** THE ** FAN ** LETTER ** HE ** WROTE ** ME **. It is
“Vault of the Beast” (1940). Synopsis: “A creature, actually the galaxy’s
greatest mathematician, is held in a huge vault on Mars, made of ultimate
metal, and whose time-lock is keyed to the ultimate prime number.” There’s
a presidential-candidate joke in there somewhere, but I can’t quite see it.