Prove $phi(p^e)not|p^et-1$











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Let p be a prime, m an odd positive integer such that $ p^e||m$, where $ e>1 $ is an integer. I am trying to show that



$$ phi(p^e)=p^e-p^{e-1}nmid p^et-1=m-1 $$



Is it enough to just say that the left-hand side will be some multiple of p whereas the right hand side will be some multiple of p minus one so the right-hand side cannot divide the left?










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  • Yes, that is enough.
    – lulu
    2 days ago










  • how would I write that though
    – mjoseph
    2 days ago








  • 1




    What you wrote is very nearly formal. If you want to say more, I'd remark that (clearly) if $a,|,b$ then any divisor of $a$ divides $b$. Now, $e>1$ implies that $p,|,p^e-p^{e-1}$. Thus, if $p^e-p^{e-1}$ were a divisor of $m-1$, $p$ would also have to be a divisor of $m-1$. But $p,|,m implies p, nmid m-1$ and we are done.
    – lulu
    2 days ago















up vote
0
down vote

favorite
1












Let p be a prime, m an odd positive integer such that $ p^e||m$, where $ e>1 $ is an integer. I am trying to show that



$$ phi(p^e)=p^e-p^{e-1}nmid p^et-1=m-1 $$



Is it enough to just say that the left-hand side will be some multiple of p whereas the right hand side will be some multiple of p minus one so the right-hand side cannot divide the left?










share|cite|improve this question
























  • Yes, that is enough.
    – lulu
    2 days ago










  • how would I write that though
    – mjoseph
    2 days ago








  • 1




    What you wrote is very nearly formal. If you want to say more, I'd remark that (clearly) if $a,|,b$ then any divisor of $a$ divides $b$. Now, $e>1$ implies that $p,|,p^e-p^{e-1}$. Thus, if $p^e-p^{e-1}$ were a divisor of $m-1$, $p$ would also have to be a divisor of $m-1$. But $p,|,m implies p, nmid m-1$ and we are done.
    – lulu
    2 days ago













up vote
0
down vote

favorite
1









up vote
0
down vote

favorite
1






1





Let p be a prime, m an odd positive integer such that $ p^e||m$, where $ e>1 $ is an integer. I am trying to show that



$$ phi(p^e)=p^e-p^{e-1}nmid p^et-1=m-1 $$



Is it enough to just say that the left-hand side will be some multiple of p whereas the right hand side will be some multiple of p minus one so the right-hand side cannot divide the left?










share|cite|improve this question















Let p be a prime, m an odd positive integer such that $ p^e||m$, where $ e>1 $ is an integer. I am trying to show that



$$ phi(p^e)=p^e-p^{e-1}nmid p^et-1=m-1 $$



Is it enough to just say that the left-hand side will be some multiple of p whereas the right hand side will be some multiple of p minus one so the right-hand side cannot divide the left?







elementary-number-theory divisibility






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited 2 days ago

























asked 2 days ago









mjoseph

477




477












  • Yes, that is enough.
    – lulu
    2 days ago










  • how would I write that though
    – mjoseph
    2 days ago








  • 1




    What you wrote is very nearly formal. If you want to say more, I'd remark that (clearly) if $a,|,b$ then any divisor of $a$ divides $b$. Now, $e>1$ implies that $p,|,p^e-p^{e-1}$. Thus, if $p^e-p^{e-1}$ were a divisor of $m-1$, $p$ would also have to be a divisor of $m-1$. But $p,|,m implies p, nmid m-1$ and we are done.
    – lulu
    2 days ago


















  • Yes, that is enough.
    – lulu
    2 days ago










  • how would I write that though
    – mjoseph
    2 days ago








  • 1




    What you wrote is very nearly formal. If you want to say more, I'd remark that (clearly) if $a,|,b$ then any divisor of $a$ divides $b$. Now, $e>1$ implies that $p,|,p^e-p^{e-1}$. Thus, if $p^e-p^{e-1}$ were a divisor of $m-1$, $p$ would also have to be a divisor of $m-1$. But $p,|,m implies p, nmid m-1$ and we are done.
    – lulu
    2 days ago
















Yes, that is enough.
– lulu
2 days ago




Yes, that is enough.
– lulu
2 days ago












how would I write that though
– mjoseph
2 days ago






how would I write that though
– mjoseph
2 days ago






1




1




What you wrote is very nearly formal. If you want to say more, I'd remark that (clearly) if $a,|,b$ then any divisor of $a$ divides $b$. Now, $e>1$ implies that $p,|,p^e-p^{e-1}$. Thus, if $p^e-p^{e-1}$ were a divisor of $m-1$, $p$ would also have to be a divisor of $m-1$. But $p,|,m implies p, nmid m-1$ and we are done.
– lulu
2 days ago




What you wrote is very nearly formal. If you want to say more, I'd remark that (clearly) if $a,|,b$ then any divisor of $a$ divides $b$. Now, $e>1$ implies that $p,|,p^e-p^{e-1}$. Thus, if $p^e-p^{e-1}$ were a divisor of $m-1$, $p$ would also have to be a divisor of $m-1$. But $p,|,m implies p, nmid m-1$ and we are done.
– lulu
2 days ago















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