OFFSET
2,3
COMMENTS
Equivalently: the maximum number of terms required to express a nonzero residue modulo n, as a sum/difference of multiplicative units which are also quadratic residues.
LINKS
N. de Beaudrap, On restricted unitary Cayley graphs and symplectic transformations modulo n, Electronic J. Combinatorics v17 (R69), 2010. See also arXiv:1002.0713.
CROSSREFS
KEYWORD
nonn
AUTHOR
Niel de Beaudrap, Feb 18 2012
STATUS
approved