Number of bicentered 6-valent 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) =19a(10) =49a(11) =103a(12) =254a(13) =583a(14) =1445a(15) =3506a(16) =8815a(17) =22082a(18) =56286a(19) =143822a(20) =371354a(21) =963250a(22) =2516822a(23) =6607348a(24) =17440933a(25) =46233833a(26) =123090070a(27) =328923702a(28) =882114742a(29) =2373351473