  We report simultaneous millimetre and infrared observations of a sequence of
very large amplitude quasi-periodic oscillations from the black hole X-ray
binary GRS 1915+105. These oscillations are near the end of a sequence of over
700 repeated events as observed at 15 GHz, and are simultaneous at the mm and
infrared wavelengths to within our time resolution (<4 min), consistent with
the respective emitting regions being physically close near the base of the
outflow. One infrared event appears to have no mm counterpart, perhaps due to
highly variable absorption. The overall radio-mm-infrared spectrum around the
time of the observations does suggest some absorption at lower frequencies. We
calculate the energy and mass-flow into the outflow for a number of different
assumptions, and find that the time-averaged power required to produce the
observed synchrotron emission cannot be much less than 3e38 erg/s, and is
likely to be much larger. This minimum power requirement is found regardless of
whether the observed emission arises in discrete ejections or in an internal
shock in a quasi-continuous flow. Depending on the similarity of the physical
conditions in the two types of ejection, GRS 1915+105 may be supplying more
power (and mass, if both have the same baryonic component) to the jet during
periods of repeated oscillations than during the more obvious larger events.
