ELI5: Explain Like I'm 5

Poly-Bernoulli number

Poly-Bernoulli numbers are a special kind of numbers that help us understand patterns in mathematics. They are named after a mathematician named Jacob Bernoulli who studied these numbers a long time ago.

Let's imagine we have a set of toys, like building blocks or puzzles. We can arrange these toys in different ways, right? We can stack them up, we can put some on top of others, or we can even spread them out in a line.

Now, let's say we want to count how many different ways we can arrange these toys. We can start by using just one toy, and there is only one way to arrange it. Then, if we have two toys, we can arrange them in two different ways - we can put one on top of the other or the other way around. If we have three toys, we can arrange them in three different ways - we can put them all in a line, stack two and put one on top, or stack one and put two on top.

Poly-Bernoulli numbers help us count all these different ways of arranging toys, or in mathematical terms, arranging things called "terms". These numbers are actually a sequence - a set of numbers that follow a pattern. The pattern is a bit tricky, but I'll try to explain it simply.

To find the Poly-Bernoulli numbers, we start with a special formula. This formula has two parts - the first part is a fancy fraction with a big number on top and a smaller number on the bottom. The second part is another fancy fraction with a different big number on top and a different smaller number on the bottom. These two parts are multiplied together to get the final Poly-Bernoulli number.

The smaller numbers on the bottom of the fractions represent the number of toys or terms we want to arrange. The bigger numbers on top of the fractions are actually a special set of numbers called the Bernoulli numbers, which were discovered by Jacob Bernoulli. The Bernoulli numbers also follow a pattern, just like the Poly-Bernoulli numbers.

The Poly-Bernoulli numbers help us understand how many different ways we can arrange these toys or terms. They can be used in many different areas of mathematics, like algebra or calculus, to solve problems and explore new ideas.

So, in simpler terms, Poly-Bernoulli numbers are a special sequence of numbers that help us count and understand patterns in arranging things or terms. They were named after a mathematician who discovered them a long time ago.