Number of bicentered trees with n nodes.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =1a(5) =1a(6) =3a(7) =4a(8) =11a(9) =20a(10) =51a(11) =108a(12) =267a(13) =619a(14) =1541a(15) =3762a(16) =9497a(17) =23907a(18) =61216a(19) =157211a(20) =407919a(21) =1063398a(22) =2792026a(23) =7365532a(24) =19535887a(25) =52037837a(26) =139213244a(27) =373820978a(28) =1007420841a(29) =2723783122