Number of unlabeled rooted trees with n nodes rooted at two indistinguishable nodes at distance 3 from each other.

A339302

Number of unlabeled rooted trees with n nodes rooted at two indistinguishable nodes at distance 3 from each other.

Terms

    a(0) =1a(1) =2a(2) =8a(3) =22a(4) =69a(5) =194a(6) =564a(7) =1584a(8) =4484a(9) =12550a(10) =35204a(11) =98412a(12) =275422a(13) =770416a(14) =2157334a(15) =6044684a(16) =16956389a(17) =47614380a(18) =133865184a(19) =376789710a(20) =1061822884a(21) =2995785714a(22) =8461975888a(23) =23928712708a(24) =67739408492a(25) =191964821890a(26) =544559201634

External references