95783024581domain: NAppears in sequencesa(n) = 6*a(n-1) - 5*a(n-2) - 4*a(n-3) - 3*a(n-4) + 2*a(n-5) + a(n-6), with a(0)=...=a(4)=0, a(5)=1.at n=21A056015