Can the uniqueness of the solution be proved? Let
$$t = \frac{3^4 + 2^k(3^3 + 2^l(3^2 + 2^m(3^1 + 2^n)))}{2^{p + n + m + l + k} - 3^5}$$
where k, l, m, n, p can only be natural numbers >=1.
The unknown t has also to be a natural number >= 1.  
While this has the trivial solution t = 1 for k = l = m = n = p = 2, I am wondering if there is any way to prove the uniqueness of this solution.
Looking at all these prime numbers at different powers, I could try to relate this to a vector space base which should imply that the numerator and the denominator are linearly independent, but since I am no expert in this, I need your help at least to know what direction to follow.
Thank you,
Catalin
 A: Because I know your equation from the consideration of cycles in the Collatz-problem (*) I'll put it into my own framework of formulae and extract an answer from that.
Let us write one "odd step" of the Collatz-transformation from positive odd $a$ to positive odd $b$ by
$$   b = {3a + 1\over 2^A}   \qquad  \text{ where $A$ is that $b$ is odd}    \tag 1     $$
Then take this to $5$ transformations writing
$$   b = {3a + 1\over 2^A}   \qquad 
  c = {3b + 1\over 2^B}   \qquad 
  d = {3c + 1\over 2^C}   \qquad  
  e = {3d + 1\over 2^D}   \qquad  
  f = {3 e+ 1\over 2^E}   \qquad    \tag 2  $$
Then we could as well write the form which notes only the exponents to make this all shorter
 $$ f=C(a;A,B,C,D,E) \tag 3 $$
and use the parameters of the transformation $N=$number-of-exponents$=$number-of-odd-steps and $S=$sum-of-exponents$=$number-of-oven-steps .
With this my exponents $(A,B,C,D,E)$ agree to your numbers $(k,l,m,n,p)  $ and $N$ is your exponent $5$ at the $3$ in the denominator.  My $S$ is your sum in the exponent at the $2$ in the denominator.                          
We can write the trivial product
$$ b \cdot c \cdot d \cdot e \cdot f =\left(3a+1 \over 2^A\right)
\left(3b+1 \over 2^B\right)\left(3c+1 \over 2^C\right)\left(3d+1 \over 2^D\right)\left(3e+1 \over 2^E\right)  \tag 4 
$$ and because we assume it's a cycle $a=f$ and we can rewrite and reorganize to the following "critical formula for cycles":
$$ a \cdot b \cdot c \cdot d \cdot e  =\left(3a+1 \over 2^A\right)
\left(3b+1 \over 2^B\right)\left(3c+1 \over 2^C\right)\left(3d+1 \over 2^D\right)\left(3e+1 \over 2^E\right)   \tag 5 $$ and then 
$$ 2^S = \left(3+\frac1a\right)\left(3+\frac1b\right)\left(3+\frac1c\right)\left(3+\frac1d\right)\left(3+\frac1e \right)   \tag 6
$$
Because all numbers $1 \le a,b,c...,e \lt \infty$ each parenthese on the rhs lies between $ 3 \lt \left(3+\frac1a\right) \le 4$ thus $$ 3^N \lt  \text{rhs} \le 4^N$$ and thus the we must also have  $$3^N \lt \text{lhs}=2^S \le 2^{2N} $$ and thus
$ 3^5=243 \lt 2^S \le 1024 =2^{10}$ which implies $ 8 \le S  \le 10$ 
The key idea of the following is:    


*

*Let us assume that $a$ is the smallest element, then it must be smaller than some average number $\alpha = \text{mean}(a,b,c,d,e) = (a+b+c+d+e)/5$
Now solving your problem by enumeration begins.      


*

*We test $S=8$
So $2^S = 256$ the next larger perfect power of $2$ larger than $3^N$.
Let us determine a solution where all numbers are equal and likely noninteger (but not $1$ because this is the trivial cycle with $S=2N=10$) 
$$ 2^8 = \left(3+\frac1 \alpha \right)^5  \\
   \alpha= { 1\over 2^{8/5} -3 } \approx  31.8   \tag 7
$$
Thus $a \le \left\lfloor \alpha \right\rfloor =31$  and we need test manually all of the candidates for $a$. That means $a \in \{5,7,11,13,17,19,23,25,29,31 \} $ . (Note, that $3 \not \mid a$ because no number divisible by $3$ can be result of an odd-step-transformation, and note that we moreover could exclude more numbers automatically from the candidate-set)
Actually testing all that possible candidates for $a$ shows that
there is no nontrivial cycle with $N=5$ and $S=8$ .                

*We test $S=9$
Using $S=9$ and $\text{lhs}=512$ gives an $\alpha=2.07$ which means that $a=1$ is required in that case, but we excluded that case because we do not want the trivial cycle.         

*We need not test $S=10$
We need not test $S=10$ because that means only the "trivial cycle" $a=b=c=d=e=1$ and $A=B=C=D=E=2$ 
Putting that all together this proves that  

Theorem 1  there is no other solution besides the trivial one for the $5$-odd-step-cycles and thus no nontrivial solution to your formula in the question.          

You see this is a fairly general ansatz which can disprove many $N$-odd-step cycles manually by few enumerations, and thus your formula in the question can be evaluated in much more generalized fashion.
Additional remark: Of course we did not need to test this actually, because it is already known that all numbers $a \lt 10^{20}$ (or so) converge to $1$ and thus cannot be member of a nontrivial cycle. But I assume you wanted a proof which you can check manually 

(*)(I've also tagged your question accordingly, hoping I meet your intentions)         
