Ulam number

When (u, v) - Ulam sequence a defined by Stanisław Marcin Ulam the Polish mathematician sequence of numbers is called. Here, u and v are natural numbers. The sequence is defined by:

For example, the (1,2)- Ulam sequence has the elements

.

5 is not part of the result, since 5 = 2 3 = 4 1 can not be represented clearly. The other sequence elements are

.

The members of a Ulam sequence are referred to as (u, v) - Ulam numbers.