A320837 For p the n-th prime congruent to 1 (mod 4), a(n) is the clique number of the subgraph of the quadratic residue (Paley) graph over F_p, the field of order p, that is induced by the set of vertices that are themselves quadratic residues.

1, 2, 2, 3, 3, 4, 4, 4, 4, 4, 5, 4, 5, 6, 6, 6, 6, 7, 6, 6, 7, 8, 6, 6, 6, 7, 7, 6, 7, 7, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 10, 8, 10, 10, 8, 8, 10, 10, 8, 9, 10, 10, 11, 10, 10, 10, 10, 10, 10, 9, 9, 10, 10, 10, 10, 10, 8, 10, 11, 10, 12, 12, 12, 10

Offset

1,2

Links

Table of n, a(n) for n=1..74.

Eric Weisstein's World of Mathematics, Clique Number

Eric Weisstein's World of Mathematics, Paley Graph

Example

a(1) = 1 because the subgraph of the Paley graph of order 5 induced by {1,4} is the two-vertex empty graph.

Crossrefs

Cf. A002144 (primes of form 4n + 1), A320757.

Sequence in context: A068509 A070319 A057142 * A098388 A371672 A157792

Adjacent sequences: A320834 A320835 A320836 * A320838 A320839 A320840

Keyword

nonn,more

Author

Jeremy F. Alm, Oct 21 2018

Status

approved