  We define an obstruction for a knot to be Z[Z]-homology ribbon, and use this
to provide restrictions on the integers that can occur as the triple linking
numbers of derivative links of knots that are either homotopy ribbon or doubly
slice. Our main application finds new non-doubly slice knots. In particular
this gives new information on the doubly solvable filtration of Taehee Kim:
doubly algebraically slice ribbon knots need not be doubly (1)-solvable, and
doubly algebraically slice knots need not be (0.5,1)-solvable. We also discuss
potential connections to unsolved conjectures in knot concordance, such as
generalised versions of Kauffman's conjecture. Moreover it is possible that our
obstruction could fail to vanish on a slice knot.
