1266660domain: NAppears in sequencesNumber of loopless tree-rooted planar maps with 3 vertices and n faces and no isthmuses.at n=29A006428Let P be a one-move "rider" with move set M={(1,2)}; a(n) is the number of non-attacking positions of two indistinguishable pieces P on an n X n board.at n=39A222308