# What can I do with the lifting the exponent lemma?

What can I do with lte (lifting the exponent) lemma?

Assume some positive integers $a,b$ with $a \gt b$ and $gcd(a,b)=1$.
Then consider the primefactorization of $f(n) = a^n - b^n$ where $n$ is again positive integer, with $m$ primefactors $$f(n) = p_1^{e_1} \cdot p_2^{e_2} \cdot \ldots p_m^{e_m}$$ Then the LTE gives you a formula, how to compute the exponents $e_k$ by a function depending on a given $n$ (and on properties of the prime $p_k$). Essentially this formula "algebraicalizes" the little theorem of Fermat and Euler's totient-theorem.