An open knot — it matches no entry in the public knot tables (KnotInfo, and Burton’s complete census of prime knots through 19 crossings), and it is not marked as a novelty. Its crossing number is proven to be at least 20. Prime knots are enumerated through c = 20, but the c = 20 data are not public, so a knot in that range may be unmatched only because it cannot be looked up. It is marked as a novelty here only once a crossing number of at least 21 is proven and, for an alternating knot, at least 25 (the alternating tables reach c = 24).