Sounds like a cancellation type of plan, have seen them numerous times over the years. From my memory, after a loss, you add that amount to the end of the series, so if your first bet was 1+7 and it lost, you would add 8 to the end, so your next bet was 1+8=9 and so on.

Cant remember the exact rules for when you win, but something along the lines of when it wins if its over a certain dividend, you cross off the two number at either end ie in above example, if your $9 bet won, you would cross off the 8 and 1, and then next bet would be 7+2.

Maybe someone can clear it up better than that, but I think its something along those lines.