Definition:Happy Number

Definition

Let $n \in \Z_{>0}$ be a positive integer.

Square the digits of $n$ and add the results.

Repeat.

If this process eventually reaches $1$, then $n$ is a happy number.

Sequence

The sequence of happy numbers begins:

$1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68, 70, 79, 82, 86, 91, 94, 97, 100, 103, 109, 129, 130, \ldots$