123316domain: NAppears in sequencesNumber of regions in a regular drawing of the complete bipartite graph K_{n,n}.at n=29A290131G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies A(x) = 1/(1 - x^a(1) - x^a(2)/(1 - x^a(3) - x^a(4)/(1 - x^a(5) - x^a(6)/(1 - ... )))), a continued fraction.at n=22A293855