The first triangular numbers are 1, 3, and 6. Here's why:

Triangular numbers can be calculated by two formulas: iterative and recursive:

Iterative formula

T (n) = 1 + 2 + 3 +… + n

Recursive Formula

T (1) = 1

T (n + 1) = T (n) + (n + 1)

The first triangular numbers are 1, 3, and 6. Here's why:

Triangular numbers can be calculated by two formulas: iterative and recursive:

Iterative formula

T (n) = 1 + 2 + 3 +… + n

Recursive Formula

T (1) = 1

T (n + 1) = T (n) + (n + 1)