

A243013


Number of graphs with n vertices and n1 edges that can be gracefully labeled.


0




OFFSET

1,4


COMMENTS

Hand calculated by grade 3 students up to term 6: (1,1,1,3,5,12...)


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

a(5) = 5: A001433 tells us that there are 6 simple graphs with 5 vertices and 4 edges. Only 5 of these can be labeled gracefully. The one that cannot is the triangular loop plus two connected nodes: ∆ / .


CROSSREFS

A001433 provides an upper bound. If the Graceful Tree Conjecture were true, A000055 would be a lower bound.
Sequence in context: A220832 A323270 A087610 * A191636 A267337 A308544
Adjacent sequences: A243010 A243011 A243012 * A243014 A243015 A243016


KEYWORD

more,nonn


AUTHOR

Gordon Hamilton, May 28 2014


STATUS

approved



