Number of square ordered rooted trees with n nodes.

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =6a(5) =5a(6) =36a(7) =84a(8) =309a(9) =890a(10) =3163a(11) =9835a(12) =32979a(13) =108252a(14) =360696a(15) =1192410a(16) =3984552a(17) =13276769a(18) =44371368a(19) =148402665a(20) =497072593a(21) =1665557619a(22) =5586863093a(23) =18750662066a(24) =62968243731a(25) =211565969511a(26) =711187790166