Number of forests of labeled rooted trees of height at most 1, with n labels, three of which are used for root nodes and any root may contain >= 1 labels.
A273653
Number of forests of labeled rooted trees of height at most 1, with n labels, three of which are used for root nodes and any root may contain >= 1 labels.
Terms
- a(0) =5a(1) =40a(2) =220a(3) =1040a(4) =4550a(5) =19040a(6) =77448a(7) =308640a(8) =1209450a(9) =4668400a(10) =17766892a(11) =66718288a(12) =247397150a(13) =906584000a(14) =3285842960a(15) =11788924992a(16) =41902786770a(17) =147668053200a(18) =516315206260
External references
- oeis: A273653