A339524 Number of unordered pairs of rooted trees with a total of n nodes and an even total of leaves.

0, 1, 1, 2, 3, 8, 18, 49, 120, 313, 802, 2120, 5591, 14942, 40033, 108108, 293094, 798839, 2185341, 6002085, 16538599, 45716952, 126727195, 352215812, 981268481, 2739930091, 7666333161, 21491833976, 60358490615, 169798048026, 478420333601

Offset

1,4

Comments

Equivalently, the number of rooted trees on n+1 nodes, where the root has degree 2, and the number of leaves is even.

Links

Table of n, a(n) for n=1..31.

Washington Bomfim, Illustration of initial terms

Index entries for sequences related to rooted trees

Formula

a(n) = A027852(n) - A339525(n).

Crossrefs

Cf. A027852, A339525.

Sequence in context: A002369 A005957 A185171 * A158448 A073192 A317722

Adjacent sequences: A339521 A339522 A339523 * A339525 A339526 A339527

Keyword

nonn

Author

Washington Bomfim, Dec 08 2020

Status

approved