Definition:Lucas Number/Sequence

Definition
The Lucas sequence begins:
 * $2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, 199, 322, 521, 843, \ldots$

Also defined as
Some sources start the sequence at $n = 1$:


 * $1, 3, 4, 7, 11, 18, 29, 47, 76, 123, 199, 322, 521, 843, \ldots$