Have any rockets ever been made with fivefold or sevenfold symmetry? Five or seven (or larger prime numbers, or multiples thereof) identical engines or boosters equally spaced around the center. (The USSR's N1's first stage had thirty engines, a multiple of five, but its symmetry was sixfold.)
Built, not only designed.
Able to climb 100 km. Need not put a payload into orbit, so sounding rockets are ok.
Need not have been flown successfully.
Such symmetries occasionally appear in other engineering disciplines, so I'd expect them to appear eventually in rocketry too, even though sixfold symmetry has a better packing density.