297619domain: NAppears in sequencesNumber of labeled nonseparable bipartite graphs on n nodes.at n=7A004100Number of labeled nonseparable (or 2-connected) bipartite graphs with 2n nodes.at n=3A005336G.f. A(x) satisfies: Product_{n>=1} (1 + x^n*A(x)) = Product_{n>=1} (1 + x^n/(1-x)^n).at n=18A352120