Question

Prove that 2^n+1 is not divisible by 31

Any ideas on how to start?
(Had to re-post due to some technical issues, Apologies)

Answer 1

@ganeshie8 , @hartnn .. need ur help

Answer 2

\(\large 2^n \equiv (2^5)^{\frac{n}{5}} \equiv 1 \mod 31\)

\(\implies 2^n+1 \equiv 2 \mod 31\)

\(\implies 31 \not | 2^n+1\)

Answer 3

just splitted 2^n into powers of 32 @***[ISURU]***