The Pell-Lucas sequence is calculated recursively by
or as a closed formula
The first numbers are
2,
2,
6,
14,
34,
82,
198,
478,
1154,
2786,
6726,
16238,
39202,
94642,
228486,
551614,
1331714,
3215042,
7761798,
18738638,
45239074,
109216786,
263672646,
636562078,
1536796802,
3710155682,
8957108166,
21624372014,
52205852194,
126036076402,
304278004998