A025568 a(n) = T(n,n+2) where T is the array defined in A025564.

1, 5, 19, 65, 211, 665, 2058, 6294, 19095, 57607, 173096, 518596, 1550367, 4627455, 13795176, 41088456, 122297643, 363828663, 1081966875, 3216725841, 9561635853, 28418162003, 84455354206, 250982289650, 745860104145, 2216567725281