Piet Hut's "coat-hanger" sequence: unlabeled forests of rooted trees with n edges, where there can be any number of components, the outdegree of each node is <= 2 and the symmetric group acts on the components.
A088325
Piet Hut's "coat-hanger" sequence: unlabeled forests of rooted trees with n edges, where there can be any number of components, the outdegree of each node is <= 2 and the symmetric group acts on the components.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =16a(6) =34a(7) =71a(8) =153a(9) =332a(10) =730a(11) =1617a(12) =3620a(13) =8148a(14) =18473a(15) =42097a(16) =96420a(17) =221770a(18) =512133a(19) =1186712a(20) =2758707a(21) =6431395a(22) =15033320a(23) =35224825a(24) =82720273a(25) =194655030a(26) =458931973a(27) =1083926784a(28) =2564305754a(29) =6075896220
External references
- oeis: A088325