To expression and gurus- Stretch a chain?

So, i've been beating my head against a lot of expression control forums and tutorials in the hopes of finding something to help me achieve this goal-

i have 16 "links" in a beaded chain and i want to simulate a stretch effect. my hopes were to learn/find an expression where the FIRST bead stays anchored at one point while the position the LAST bead in the chain effects the placement of all the bead in between the two. the beads would grow more equidistant from each other as the FIRST and LAST beads become further and further apart to simulate stretching. make sense?

any ideas... anywhere?

muchos thankos,
drew