The answer is 1, 5 and 8.
Checking by hand for n=1,2,…,6, we see that 1 and 5 work. For n≥7, 2n+7 should be a prime number. Because, otherwise there exists a prime divisor of 2n+7 which is less than or equal to n since 2n+7 is odd, but it divides n!.
Now let 2n+7=p≥21 where p is a prime number. Then the condition is equivalent to (2p−7)!≡1(modp). Wilson's theorem gives that (p−1)!≡−1(modp). On the other hand
(p−1)!≡(−1)2p−7⋅(2p−7)!2⋅2p−5⋅2p−3⋅2p−1⋅2p+1⋅2p+3⋅2p+5≡(−1)2p−164225(modp)
Thus we obtain 225≡(−1)2p+164(modp).
If p≡1(mod4), then p∣225+64=172 but p≥21, no solution exists.
If p≡3(mod4), then p∣225−64=7⋅23. As p≥21 we have p=23, that is n=8 and it satisfies the condition.