3723986domain: NAppears in sequencesPisot sequence E(10,18), a(n)=[ a(n-1)^2/a(n-2)+1/2 ].at n=22A014006Number of essentially parallel series-parallel networks with n unlabeled edges, multiple edges not allowed.at n=20A058385Essentially series series-parallel networks with n unlabeled edges, multiple edges not allowed.at n=20A058386