Lucas sequence

The Lucas Sequence is a series of numbers that starts with 2 and 1, and each subsequent number in the sequence is the sum of the two previous numbers. So, the third number in the sequence is 2+1=3, the fourth number is 1+3=4, the fifth number is 3+4=7, and so on. This is similar to the Fibonacci sequence but starts with 2 instead of 1.

Think of it like building a tower out of blocks. You start with two blocks on top of each other. Then you add one more block on top to get three blocks. Then you add another block on top of those three to get four blocks. You keep adding one block at a time to the top of the tower to get the next number in the sequence.

This sequence is named after a man named Édouard Lucas who was a mathematician and wrote about it in the late 1800s. It is often used in math and computer programming because it has some interesting properties and patterns.