A373721 Number of trees with n nodes which have nodes that cannot be gracefully labeled '0'.

0, 0, 0, 0, 0, 0, 1, 1, 3, 3, 4, 5, 9, 9, 14

Offset

0,9

Comments

Also called non-0-ubiquitous.

Links

Table of n, a(n) for n=0..14.

Frank Van Bussel, 0-Centred and 0-ubiquitously graceful trees, Discrete Mathematics 277.1-3 (2004): 193-218. See Section 2.

Example

For n=6 the tree with a-b-c-d-e
                             \
                              f
has no graceful solution with 'c' labeled as '0'.

Crossrefs

Sequence in context: A104806 A241442 A363091 * A043551 A162888 A337402

Adjacent sequences: A373718 A373719 A373720 * A373722 A373723 A373724

Keyword

nonn,more

Author

Michael Arnold, Jun 15 2024

Status

approved