What is delight number?

A delight number, also known as a happy number, is a positive integer that eventually reaches 1 when replaced by the sum of the square of each digit in the number.

For example, let's take the number 19: 1^2 + 9^2 = 1 + 81 = 82 8^2 + 2^2 = 64 + 4 = 68 6^2 + 8^2 = 36 + 64 = 100 1^2 + 0^2 + 0^2 = 1

Since the number 19 eventually reaches 1 in this process, it is considered a delight/happy number. On the other hand, if the number reaches a cycle of numbers that do not include 1 (such as 4, 16, 37, 58, 89, 145, 42, 20), then it is not a delight number.

Delight numbers are a fascinating mathematical concept and can be studied in the field of number theory.