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
Examples
a(1) = 1 because the subgraph of the Paley graph of order 5 induced by {1,4} is the two-vertex empty graph.
Links
- Eric Weisstein's World of Mathematics, Clique Number
- Eric Weisstein's World of Mathematics, Paley Graph