Apparently, this user prefers to keep an air of mystery about them.
15 In how many ways we can place $N$ mutually non-attacking knights on an $M \times M$ chessboard? feb 15 '13
5 Given $A$ and $B$, how many positive integers $N$ such that $N\times B$ has at least one divisior $D$ that lies in $N \lt D \le A$? feb 15 '13