Number of unlabeled 4-ary cacti having n polygons.

Terms

a(0) =1a(1) =1a(2) =4a(3) =10a(4) =44a(5) =197a(6) =1228a(7) =7692a(8) =52828a(9) =373636a(10) =2735952a(11) =20506258a(12) =156922676a(13) =1221179926a(14) =9642496488a(15) =77092885016a(16) =623121750844