8. 3=2+1, 4=3+2-1, 6=4+3-2+1,8=6+4-3+2-1,12=8+6-4+3-2+1. Funny question,... By math,you can put any number x and you can find a polynomial satisfing :P(1)=1, P(2)=2...P(6)=x....