A036661 Number of n-node rooted labeled trees with deg <= 4 at root and outdegree <= 2 elsewhere.

1, 1, 2, 4, 8, 15, 32, 66, 142, 306, 672, 1483, 3316, 7446, 16859, 38353, 87735, 201510, 464801, 1075744, 2498053, 5817576, 13585231, 31801732, 74615404, 175433624, 413281276, 975355639, 2305763635, 5459480822, 12945857671

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Index entries for sequences related to rooted trees
• Index entries for sequences related to trees

Crossrefs

Cf. A000671, A001190.

Formula

G.f.: A(x) = x*cycle_index(S4, f), where f = A001190(x)/x.