# Definition:Ulam Number

## Definition

The sequence of Ulam numbers is defined as:

It begins $1, 2, 3$
Each new term is the next to be uniquely the sum of $2$ previous terms in the sequence.

## Sequence of Ulam Numbers

The sequence of Ulam numbers begins as follows:

$1, 2, 3, 4, 6, 8, 11, 13, 16, 18, 26, 28, 36, 38, 47, 48, 53, 57, 62, 69, \ldots{}$

## Also see

• Results about Ulam numbers can be found here.

## Source of Name

This entry was named for Stanisław Marcin Ulam.