Thursday, July 13, 2017

number theory - Prove that : $2^{2^{n}}+1mid 2^{x_{n}}-2$ with $n=1,2,3...$

Question :



Let $n>0$ a natural number Use the following inequality $2^{n}≥n+1$ to prove that :



$2^{2^{n}}+1\mid 2^{x_{n}}-2$ where :



$x_{n}=2^{2^{n}}+1$




My attempt :



I think use induction :



$n=1$ then $x_{n}=5$ so $30\mid 5$ correct



Now for $n+1$ we will prove that :



$x_{n+1}\mid 2^{x_{n+1}}-2$.




I don't know how prove it using $2^{n}≥n+1$.



If any one know other method please drop here



Thanks!

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