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1 vote
1 answer
43 views

Prove that the 5-adic valuation of $(10^{k+t}+10^t+1)^c-1$ is $t+v_5(c)$

Here is a result of mine that I really wish to be strictly proven (I need it as an intermediate lemma for a theorem). Let $v_5(a)$ indicate the $5$-adic valuation of $a \in \mathbb{Z}^+$. How can we ...
Marco Ripà's user avatar
  • 1,160
4 votes
3 answers
225 views

Prove that $x^2+px+p^2$ is a factor $(x+p)^n-x^n-p^n$, if $n$ be odd and not divisible by $3$.

Question: Prove that $x^2+px+p^2$ is a factor of $(x+p)^n-x^n-p^n$, if $n$ is odd and is not divisible by $3$. My approach: $$(x+p)^n-x^n-p^n=\sum_{r=0}^n\limits {n\choose r} x^{n-r}p^r-x^n-p^n$$ What ...
MKS's user avatar
  • 730
5 votes
3 answers
391 views

"Binomial coefficients" generalized via polynomial iteration

This is a question I will answer myself immediately by repeating one of my old AoPS posts, since the latter post no longer renders on AoPS. Convention. In the following, whenever $A$ is a ...
darij grinberg's user avatar