95459694592domain: NAppears in sequencesa(0) = 1, a(1) = 2, for n > 1, a(n) = 4*a(n-1) - 2*a(n-2).at n=21A003480Pisot sequence P(2,7): a(0)=2, a(1)=7, thereafter a(n+1) is the nearest integer to a(n)^2/a(n-1).at n=20A020727Binomial transform of (Pell(-n)+Pell(n))/2.at n=22A094038