2878981domain: NAppears in sequencesa(1) = 1, a(2) = 2, a(3) = 6; a(n) = 5*a(n-1) - 5*a(n-2) + a(n-3) for n > 3.at n=12A101265a(0) = 1, a(1) = 1, a(2) = 2; for n > 2, a(n) = 5*a(n-1) - 5*a(n-2) + a(n-3).at n=13A101879a(n) = Sum_{k=0..floor(n/2)} 2^(n-2*k) * binomial(2*n-2*k,2*k).at n=12A387689