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

0,3

Links

Table of n, a(n) for n=0..30.

Index entries for sequences related to rooted trees

Index entries for sequences related to trees

Formula

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

Crossrefs

Cf. A000671, A001190.

Sequence in context: A086125 A227236 A061030 * A145671 A316522 A317712

Adjacent sequences: A036658 A036659 A036660 * A036662 A036663 A036664

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved