Number of unlabeled 5-trees on n nodes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =1a(7) =2a(8) =5a(9) =15a(10) =64a(11) =342a(12) =2321a(13) =18578a(14) =168287a(15) =1656209a(16) =17288336a(17) =188006362a(18) =2105867058a(19) =24108331027a(20) =280638347609