627359043domain: NAppears in sequencesa(n) = 2*a(n-1) + 2*a(n-2) - a(n-3) with a(-1) = 1, a(0) = 1, a(1) = 1.at n=23A061646Number of partitions of the vertices of the n-ladder graph into total dominating sets.at n=22A392415