Giải:
Ta có: (n^2+4⋮n+1)
(Rightarrow n^2+n+4-n⋮n+1)
(Rightarrow nleft(n+1 ight)+4-n⋮n+1)
(Rightarrow4-n⋮n+1)
(Rightarrow5-left(n+1 ight)⋮n+1)
(Rightarrow5⋮n+1)
(Rightarrow n+1inleft{1;-1;5;-5 ight})
(Rightarrow ninleft{0;-2;4;-6 ight})
Vậy (ninleft{0;-2;4;-6 ight})