## Prime or Composite? With proof

For students of class 11-12 (age 16+)
Hasib
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### Prime or Composite? With proof

Determine the following number is prime or composite $2^{2^{2011}+2011}+1$

HINTS: There is a generalize form of this problem.
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Moon
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### Re: Prime or Composite? With proof

"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

learn how to write equations, and don't forget to read Forum Guide and Rules.

Hasib
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### Re: Prime or Composite? With proof

hahaha. I am a grt fool. I dont check that, the power of 2 is odd. Thus the solution is so easy. By the way, the main problem is to prove $2^{2^k+s}+1$ is a composite number while $s \in \{1,2,3,4,...,(2^k-1)\}$.

A man is not finished when he's defeated, he's finished when he quits.

Tahmid Hasan
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### Re: Prime or Composite? With proof

actually i was the first one to prove it and sakal roy generalized it
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Masum
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Let $s=2^lm$ with $m$ odd.Then we have $l<k$ and then $2^{2^k+s}+1=2^{2^l(2^{k-l}+m)}+1$ with $2^{k-l}+m$ odd
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