Reversion of g.f. (beginning with constant term) for number of trees with n nodes.

Terms

a(0) =1a(1) =-1a(2) =1a(3) =-1a(4) =0a(5) =4a(6) =-16a(7) =46a(8) =-111a(9) =228a(10) =-379a(11) =389a(12) =393a(13) =-3810a(14) =14169a(15) =-39735a(16) =91861a(17) =-172623a(18) =225378a(19) =10246a(20) =-1347935a(21) =5843671a(22) =-17779693a(23) =43942706a(24) =-89033228a(25) =133666868a(26) =-64088688a(27) =-508956437a(28) =2636138606a(29) =-8664888857