数学上の未解決問題
Lehmer's totient problem: if φ(n) divides n − 1, must n be prime?
友愛数は無数にあるか?
Are there any pairs of amicable numbers which have opposite parity?
互いに素な友愛数のペアはあるか?
婚約数は無数にあるか?
Are there any pairs of betrothed numbers which have same parity?
The Gauss circle problem – how far can the number of integer points in a circle centered at the origin be from the area of the circle?
Is π a normal number (its digits are "random")?
Casas-Alvero conjecture
Find value of De Bruijn–Newman constant
3つの立方数の和 : Which integers can be written as the sum of three perfect cubes?
ABC予想