Similar to ペル方程式

Coprime integers

Taxicab number

Powerful number

Unitary divisor

Chebyshev function

Central binomial coefficient

Superabundant number

Superperfect number

Harmonic divisor number

Harmonic number

Diophantine approximation

Tate–Shafarevich group

Tate twist

Dirichlet series

Dirichlet character

Dirichlet L-function

Dirichlet's unit theorem

Dedekind zeta function

Dedekind eta function

Ducci sequence

Narcissistic number

Fermat's theorem on sums of two squares

Dihedral prime

Nesbitt's inequality

Néron model

Field norm

Nontotient

Harshad number