A207507 Diameters of quadratic unitary Cayley graphs on the integers modulo n.

1, 1, 2, 2, 3, 1, 4, 2, 5, 1, 6, 2, 3, 3, 4, 2, 3, 1, 5, 3, 3, 1, 12, 2, 3, 2, 4, 2, 5, 1, 4, 3, 3, 3, 6, 2, 3, 2, 5, 2, 4, 1, 4, 3, 3, 1, 12, 2, 5, 2, 3, 2, 3, 3, 4, 3, 3, 1, 6, 2, 3, 3, 4, 3, 4, 1, 3, 3, 5, 1, 12

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

Table of n, a(n) for n=2..72.

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

Sequence in context: A035207 A324829 A294618 * A278537 A331803 A325184

Adjacent sequences: A207504 A207505 A207506 * A207508 A207509 A207510

Keyword

nonn

Author

Niel de Beaudrap, Feb 18 2012

Status

approved