Secondary Special Camp 2011: NT P 1

[tarek like math]

that's what i say when 2n+1=prime then it restrict answer bcz a prime must has no factor so i say in this case d=2n+1 and i don't think about 1. that's different what u say and i said. nothing to be anxious much. but ur discussion about this solution is very helpful. also ur replies on my reply clarify things as easy as possible. it will help all reader of this post. thank you.