Fibonacci numbers start with $F_0 = 0$ and $F_1 = 1$, then each new term is the sum of the previous two.

That recurrence $F_n = F_{n-1} + F_{n-2}$ produces the familiar sequence $0,1,1,2,3,5,8,dots$.

The first-screen cards help you see the rapid growth instead of only reading a block of text output.