Prime or Composite?????????????/

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prodip
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Prime or Composite?????????????/

Unread post by prodip » Sun Jan 02, 2011 6:53 pm

Is \[\frac{2^{58}+1}{5} \] prime or composite?

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Moon
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Re: Prime or Composite?????????????/

Unread post by Moon » Sun Jan 16, 2011 8:54 pm

Don't ask me how I found it ;)
http://www.wolframalpha.com/input/?i=10 ... 8%2B1}%2F5

\[\dfrac{2^{58}+1}{5}=107367629 \times 536903681\]
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

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ishfaqhaque
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Re: Prime or Composite?????????????/

Unread post by ishfaqhaque » Mon Jan 17, 2011 2:25 pm

:shock: how did you find this

prodip
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Re: Prime or Composite?????????????/

Unread post by prodip » Fri Jan 21, 2011 12:13 pm

মুন ভাইয়া আমি তো সেই আঁধারেই থাকলাম। :roll:
শুধু জানলাম এটা composite.


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Moon
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Re: Prime or Composite?????????????/

Unread post by Moon » Fri Jan 21, 2011 1:02 pm

হা হা...রহস্য ফাঁস হয়ে গেল। :)
তবে এই ধরণের সমস্যা কোন অলিম্পিয়াডে আসার কোন সম্ভাবনা নাই এবং এইটা কম্পিউটার ছাড়া সমাধানের কোন উপায় নাই বইলাই মনে হয়।
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

Please install LaTeX fonts in your PC for better looking equations,
learn how to write equations, and don't forget to read Forum Guide and Rules.

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