Number of rooted binary normal unlabeled galled trees with n leaves and exactly 1 gall.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =4a(5) =15a(6) =48a(7) =148a(8) =435a(9) =1250a(10) =3512a(11) =9726a(12) =26587a(13) =71975a(14) =193200a(15) =515051a(16) =1364896a(17) =3598794a(18) =9447028a(19) =24704031a(20) =64382465a(21) =167288460a(22) =433512724a(23) =1120719444a(24) =2891035926a(25) =7443225226a(26) =19129208972a(27) =49082742607a(28) =125752279124a(29) =321744111359