# Graceful graphs all of whose vertices are labelled with primes or squares

Do graceful graphs exist with more than any arbitrarily large number of vertices, all of which are labelled with a prime or non-negative square number.

Recall that a graceful graph is a graph with m edges whose vertices can be labelled with some subset of the integers between 0 and m inclusive, no two vertices sharing a label, and each of its edges uniquely identified by the absolute difference between its end points (so that this magnitude lies between 1 and m inclusive).

There is evidence (https://math.stackexchange.com/questions/3253495/integers-as-differences-of-squares-and-primes/3253666#3253666) that the answer to this is no, but a proof is lacking.

This graphs shows the number of numbers between $$1$$ and $$n$$ that are left out.