Definition:Lucas Number

Definition
The Lucas numbers are a sequence which is formally defined recursively as:


 * $L_n = \begin{cases}

2 & : n = 0 \\ 1 & : n = 1 \\ L_{n-1} + L_{n-2} & : \text{otherwise} \end{cases}$

Also defined as
Some sources begin this sequence:
 * $1, 3, 4, 7, \ldots$

Also see

 * Definition:Fibonacci Numbers