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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
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
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
KEYWORD
nonn,more
AUTHOR
Jeremy F. Alm, Oct 21 2018
STATUS
approved