A= 3^(2n+3)•4^(2n+3)-2^(2n+1)•6^(2n+3)
A=3^2n·3^3·2^4n·2^6 - 2^2n·2·2^2n·2^3·3^2n·3^3
A=3^(2n+3) ·2^(4n+6)- 3^(2n+3) ·2^(4n+4)
N=3^(2n+2) ·2^(4n+4)(3 ·4-3)
N=[3^(n+1) ·2^(2n+2)]^2 ·9
N=[3^(n+1) ·2^(2n+2) ·3]^2
sau N=[3^(n+2) ·2^(2n+2)]^2, deci e p.p.