Exercițiul 2 vă rog!

daca n=0 => -4 ∉ N
daca n=1 => 3-4= -1 ∉ N
daca n=2 => 6-4=2 ∈ N
daca n=3 => 9-4=5 ∈N
daca n=4 => 12-4=8 ∈ N
daca n=5 => 15-4=11 ∈ N
......
daca n=9 => 27-4=23 ∈ N => card(M)=8