M is the number of six-element subsets that can be chosen from the set of the first 15 positive integers so that at least three of the six numbers are consecutive.
Find M.

(In reply to 2 computer solutions; the second is probably right by Charlie)

Printing out all the positional combinations of x's for the chosen numbers shows they are all unique-- all 2155 of them.

Posted by Charlie on 2016-02-09 16:15:26