Number of mixed Husimi trees with n nodes; or polygonal cacti with bridges.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =9a(6) =23a(7) =63a(8) =188a(9) =596a(10) =1979a(11) =6804a(12) =24118a(13) =87379a(14) =322652a(15) =1209808a(16) =4596158a(17) =17657037a(18) =68497898a(19) =268006183a(20) =1056597059a(21) =4193905901a(22) =16748682185a(23) =67258011248a(24) =271452424286