Given a doubled knot with the unknot taken as the base knot 
,
the companion knot 
of 
is called a twist knot with 
twists. As illustrated above, the following knots are twist knots (Rolfsen 1976,
p. 112).
The unknot and stevedore's knot are the only twist knots that are slice knots (Casson and Gordon 1975; Rolfsen 1976, p. 226).
