Turkish NMO First Round - 2012 Problem - 12 {Combinatorics}
Source:
July 1, 2012
Problem Statement
How many subsets of the set {1,2,3,4,5,6,7,8,9,10} are there that does not contain 4 consequtive integers?<spanclass=′latex−bold′>(A)</span>596<spanclass=′latex−bold′>(B)</span>648<spanclass=′latex−bold′>(C)</span>679<spanclass=′latex−bold′>(D)</span>773<spanclass=′latex−bold′>(E)</span>812