prob015: Schur's lemma

proposed by Toby Walsh
tw@cs.york.ac.uk

References

Guy, R. K. ``Schur's Problem. Partitioning Integers into Sum-Free Classes'' and ``The Modular Version of Schur's Problem.'' §E11 and E12 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 209-212, 1994.

Ramsey numbers are closely related, and are described in prob017.