Number of planar planted trees with n non-root nodes and every 2-valent node isolated.

A061639

Number of planar planted trees with n non-root nodes and every 2-valent node isolated.

Terms

    a(0) =0a(1) =1a(2) =1a(3) =1a(4) =4a(5) =10a(6) =28a(7) =85a(8) =262a(9) =829a(10) =2677a(11) =8776a(12) =29143a(13) =97825a(14) =331381a(15) =1131409a(16) =3889381a(17) =13450744a(18) =46764532a(19) =163357807a(20) =573064849a(21) =2018027719a(22) =7131064045a(23) =25278463756a(24) =89866690732a(25) =320328538033

External references