Răspuns:
A=2^n+1 + 3•2^n+ 2^n+3
n=2 =>A= 2^3 + 3•2^2 + 2^5
A=8+12+32
A=52
n=3 => A=2^4 +3•2^3 + 2^6
A=16+24+32
A=72
A=2^n •( 2 +3 +2^3)
A=13•2^n
A divizibil cu 4, dar nu si cu 16 => 2^2 ≤ 2^n <2^4
=> n∈{2,3}
