3356004888domain: NAppears in sequencesa(n) = sigma(n)*Pell(n), where sigma(n) = A000203(n), the sum of divisors of n.at n=21A204271Number of 3 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 1 1 1 vertically.at n=22A207846