Well, since this author didn't even bother to correct their "hint", here's more than enough hints to solve:
All the 3s are in the center except in L11 where it starts in C9.
L7: C2-3
L8: C1, 4, 14
L9: C13, 15
L10: C5, 12
These are duplicated symmetrically, except L14:
C1: L20,21
C2: L11-12, 18-19, 22-23
C3: L13, 17, 24
C4: L14-16, 25
ligne 20 / 1n 2b 1n 1b 4n 4b 1n
colonne 9 / 14n 1b 1n 1b 1n 1b 2n 3b 1n
All the 3s are in the center except in L11 where it starts in C9.
L7: C2-3
L8: C1, 4, 14
L9: C13, 15
L10: C5, 12
These are duplicated symmetrically, except L14:
C1: L20,21
C2: L11-12, 18-19, 22-23
C3: L13, 17, 24
C4: L14-16, 25