quy luat cua day tren la :3=2x2-1
5=2.3-1
14=3.5-1
.......................
vay so tiep theo ta goi la x nhe cac bn
x se bang 2 so dung truoc no nhan voi nhau roi tru 1
x=5.14-1=69
vay ta co day so:2,2,3,5,14,69,965
................................neu dung nho h cho mk nha cac ban...........................................................