This problem is everywhere!
18:15
an absolutely surprising final solution to this functional equation.
17:37
Japanese Mathematical Olympiad | 2004 Q2
17:42
This problem writer is clever.
27:26
This open problem taught me what topology is
21:09
Every calculus teacher I know skips this!!
17:26
Researchers thought this was a bug (Borwein integrals)
18:42
a nice functional equation.
18:56