3 lights forming a triangle, converging, disappearing. Then reappearing forming a triangle, converging then disappearing again.

We were the pilots from United 1325 DEN-PDX. About 50 miles from the northwestern border of Colorado on a heading of 285 at 38,000ft we noticed a series of lights, appearing at first to look like 3 light bright stars or satellites forming a triangle, at 2'clock high. As we watched this the lights moved going west to east then up and down converging and then disappearing. They stayed in our approximate 1:30 to 2'clock position appearing to be well above us. The patterner of forming a triangle, converging, moving, and then disappearing continued every 2-3 minutes for approximately 20 minutes as we passed the Wyoming border and then into Utah. They appeared to be far away at a high altitude.
The other pilot I was flying with mentioned that he had seen the same moving pattern of lights on a different day in the same location in northwestern Colorado.