C(7,4,3) = 12

Method of Construction: simple construction: combined c(v-1,k,t) and c(v-1,k-1,t-1)

 1  2  3  6 
 1  2  4  6 
 1  2  5  6 
 1  2  5  7 
 1  3  4  5 
 1  3  4  7 
 1  5  6  7 
 2  3  4  5 
 2  3  6  7 
 2  4  6  7 
 3  4  5  6 
 3  4  5  7