### Brain Teasers

# Happily Alone

What are the missing numbers?

7, 13, 19, 23, 31, __, __, 103, 109, 139, 167, 193, 239

7, 13, 19, 23, 31, __, __, 103, 109, 139, 167, 193, 239

### Hint

These numbers are all prime.### Answer

79, 97These are the first 13 happy prime numbers.

A number is prime when it has exactly 2 whole number divisors: 1 and itself.

A happy number is defined by the following process. Starting with any positive whole number, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1.

For example:

23

2^2+3^2

4+9

13

1^2+3^2

1+9

10

1^2+0^2

1

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