Log of e.g.f. for trees A000055(n-1).

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =-4a(6) =12a(7) =-30a(8) =70a(9) =-282a(10) =2195a(11) =-17680a(12) =122815a(13) =-752054a(14) =4449773a(15) =-30013564a(16) =259850583a(17) =-2638753310a(18) =27217133989a(19) =-269838173334