The 21n diagrams have the proposed resultant classification

A free $21n$ knot is the free knot diagram formed from the $21$-tangle and a free $n$-tangle, as used in the source. Resultants are knots obtained by assigning all free crossings. $21n$ resultant-classification conjecture. A free $21n$ knot produces $2$ copies of the $3_{n-1}$ knots, $2n$ copies of the $3_{n-3}$ knots, and $2{n\choose k/2}$ copies of the $2_{n-k}$ knots, for $3\leq n-k\leq n-4$. The source says that the preceding results classify a large majority of the resultants and that the remaining classification is planned; no proof or resolution of this full claim is supplied.