x apartine D16 => D16={1,2,4,8,16} => x={1,2,4,8,16}
3x+1 apartine M4 => M4={0,4,8,12,16,20,24,28,...}
3x+1=0
3x=-1->imposibil
3x+1=4
3x=3
x=1
3x+1=8
3x=7->imposibil
3x+1=12
3x=11->imposibil
... si aflam ca x=1,5,9,15,19,... => x={1,5,9,15,19,...}
x={1,2,4,8,16} intersectat x={1,5,9,15,19,...}={1} => C={1}