Prove the sequence is an=nnn! not bounded above.
This is exercise 1.4.2 in Introduction to Analysis by Arthur P. Mattuck.
The hint given in the book is "Show that an>n".
I attempted to show this using induction.
Basic Step
a1=111=1≯1
a2=222=2≯2
a3=333=92>3
Inductive Step
Show nnn!>n⟹(n+1)(n+1)(n+1)!>n+1
This is where I get stuck.
I reduced the sequence so (n+1)(n+1)(n+1)!=(n+1)nn!.
I figure the next step is to show (n+1)nn!>nnn!+1, but I am not sure how to get there.
I also looked at this question since it was working with a similar equation, but I wasn't able to derive anything out of the discussion that could lead to an answer.
Edit:
Side Question
Does this need to be solved using induction, or are there other methods of directly proving this result? Is induction a clumsy or unwieldy tool for this problem?
Answer
an=n⋅n⋯n1⋅2⋯n=n1n2⋯nn>n1=n
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