Number of regular bipartite simple graphs on n nodes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =3a(5) =1a(6) =4a(7) =1a(8) =6a(9) =1a(10) =8a(11) =1a(12) =18a(13) =1a(14) =40a(15) =1a(16) =230a(17) =1a(18) =4296a(19) =1a(20) =431206a(21) =1a(22) =162267272a(23) =1a(24) =201636689771a(25) =1a(27) =1a(29) =1a(31) =1a(33) =1