### Home > A2C > Chapter 2 > Lesson 2.1.4 > Problem 2-53

2-53.

Refer to sequences (c) and (i) in problem 2-43. How are these two sequences similar?

Sequences such as those in parts (c) and (i) can be called

**quadratic sequences.**Why do you think they are called this?Notice that all the numbers in (c) are perfect squares.

Notice that 0-18 in (i) are double 0-9 in (c).

The numbers in the sequence in part (e) from problem 2-43 are called Fibonacci numbers. They are named after an Italian mathematician who discovered the sequence while studying how fast rabbits could breed. What is different about this sequence than the other three you discovered?

Check the sums of pairs of numbers in the sequence.