Source: wikibot/ulam-number
= Ulam number
{wiki=Ulam_number}
Ulam numbers are a sequence of integers that start with the numbers 1 and 2. Subsequent Ulam numbers are generated using a specific rule: each Ulam number is the smallest positive integer that can be expressed as the sum of two distinct earlier Ulam numbers in exactly one way. The sequence begins as follows: 1. The first two Ulam numbers are 1 and 2.