2的m次方=a
2的n次方=b
2^(2m)=(2^m)^2=a^2
2^(3n)=(2^n)^3=b^3
2^(m+n)+2(m+3n)
=2^n*2^m+2^m*2^(3n)
=b*a+a*b^3
=ab(1+b^2)