Number of forests of labeled rooted trees of height at most 1, with n labels, two of which are used for root nodes and any root may contain >= 1 labels.
A273652
Number of forests of labeled rooted trees of height at most 1, with n labels, two of which are used for root nodes and any root may contain >= 1 labels.
Terms
- a(0) =2a(1) =9a(2) =30a(3) =90a(4) =255a(5) =693a(6) =1820a(7) =4644a(8) =11565a(9) =28215a(10) =67650a(11) =159822a(12) =372827a(13) =860265a(14) =1966200a(15) =4456584a(16) =10027161a(17) =22413483a(18) =49807550a(19) =110100690a(20) =242221287a(21) =530579709a(22) =1157628180a(23) =2516582700a(24) =5452595525a(25) =11777605983a(26) =25367150970a(27) =54492397974a(28) =116769423795
External references
- oeis: A273652