Question

18. Let \( f(n)=\frac{4 n+\sqrt{4 n^{2}-1}}{\sqrt{2 n+1}+\sqrt{2 n-1}}, n \in N \) then the remainder when \( f(1)+f(2)+f(3)+\ldots+f(60) \) is divided by 9 is

Answer 1

saucy6928, hello

What a problem.  The remainder when the sum of this sequence is divided by 9 is: 8

And as a side note, if anyone is interested the sum of this sequence is: 665