NZ-NZMO 2024 Problem 4

A dot-trapezium consists of several rows of dots such that each row contains one more dot than the row immediately above (apart from the top row). For example here is a dot-trapezium consisting of 15 dots, having 3 rows and 4 dot in the top row.

A positive integer $n$ is called a trapezium- number if there exists a dot- trapezium consisting of exactly $n$ dots, with at least two rows and at least two dots in the top row. How many trapezium- numbers are there less than 100?