The smallest such prime...
14:28
A mysterious factorial equation.
20:14
Irish Math Olympiad | 2009 Question 3
14:30
This is always even??
1:02:35
Number Theory: Queen of Mathematics
14:33
a RARE mistake from Euler (AIME 1989)
10:48
Two math problems from Africa.
13:26
A Fun One from the Vietnamese IMO
14:27