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9 votes
2 answers
440 views

How to prove this sum involving powers of cosec is an integer?

It is claimed that the following function produces only integer values for all integer $m \geq 1$, $N \geq 2$. $F(m,N)=\frac{N^m}{2^m}\displaystyle \sum_{j=1}^{N-1} \operatorname{cosec} ^{2m}\left(\...
MilesB's user avatar
  • 201
1 vote
0 answers
156 views

Fejer-Jackson-like inequality with divisor sum

A question was recently asked about a generalization of the Fejer-Jackson inequality $$\sum_{k=1}^n \frac{\sin kx}{k}\gt 0 \quad \forall\: n\in\mathbb{Z}^+\: \text{and}\: 0\lt x\lt\pi$$ to ...
ljk's user avatar
  • 105