- neu n=0 thi n^2+5n+1=1(loai vi 1 ko phai so nguyen to)
-neu n=1 thi n^2+5n+1=7(la so nguyen to,chon)
....
vi n nho nhat nen n=1
- neu n=0 thi n2+5n+1=1 ko phai so nguyen to(loai)
- neu n=1 thi n2 +5n+1=7(la so nguyen to, chon)
......
vi n la nho nhat nen n=1