Similar to 中心つき三角数

Twin prime

Practical number

Blum integer

Friedman number

Brocard's problem

Proth number

Partition function (number theory)

Square-free integer

Square triangular number

Square number

Heegner number

Perrin number

Bell number

Pell number

Bernoulli number

Markov number

Mian–Chowla sequence

Mersenne number

Motzkin number

Divisor

Amicable numbers

Good prime

Prime quadruplet

Lychrel number