Convex series

Imagine you have a nice round bowl, and you want to fill it up with marbles. You start placing marbles into the bowl, but you make sure that each marble is placed a little bit higher than the one before it. This makes the top of the pile look like a hill with a rounded shape.

This is kind of like a convex series. A series is just a sequence of numbers that follow a pattern. A convex series is a sequence where each number is a little bit higher than the one before it, and the pattern forms a rounded hill shape, just like the marbles in the bowl.

So, to summarize, a convex series is a sequence of numbers that increase slightly and form a curved shape. It's like a hill made out of numbers.