A=2× 3^(12n+5) + 4× 3^(12n+4) - 27 × 3^(12 n+ 1)=
=2× 3^(12n+5) + 4× 3^(12n+4) - 3³ × 3^(12 n+ 1)=
=2× 3^(12n+5) + 4× 3^(12n+4) - 3^(12 n+4)=
=3^(12n+4)(2×3+ 4× 3^0 - 3^0=
=3^(12n+4)(6+ 4 -1)=
=3^(12n+4) × 3²=
=3^(12n+6) =
=[3^(6n+3)]² = patrat perfect
=[3^(4n+2)]³ = cub perfect