Răspuns:
a=2×3^(12n+5)+2^2×3^(12n+4)-2×7×3^(12n+3)
a=2×3^(12n+3)(3^2+2×3-7)
a=2×3^(12n+3)(9+6-7)
a=2×3^(12n+3)×8
a=16×3^(12n+3)
a=16×3×3^(12n+2)
a=48×3^(12n+2)---->48|a--->a divizibil cu 48, oricare ar fi n aparține N
