2,1

J. Brillhart, D. H. Lehmer and E. Lehmer, Bounds for pairs of consecutive seventh and higher power residues, Math. Comp. 18 (1964), 397-407.

J. H. Jordan, Pairs of consecutive power residues or nonresidues, Canad. J. Math., 16 (1964), 310-314.

W. H. Mills, Bounded consecutive residues and related problems, pp. 170-174 of A. L. Whiteman, ed., Theory of Numbers, Proc. Sympos. Pure Math., 8 (1965). Amer. Math. Soc.

P. Erd\"{o}s and R. L. Graham, Old and New Problems and Results in Combinatorial Number Theory. L'Enseignement Math., Geneva, 1980, p. 87.

Every large prime has a pair of consecutive quadratic (n=2) residues which appear not later than 9,10, so a(2)=9 - comment from Len Smiley (smiley(AT)math.uaa.alaska.edu).

Cf. A000236.

Adjacent sequences: A000442 A000443 A000444 this_sequence A000446 A000447 A000448

Sequence in context: A126631 A046150 A124131 this_sequence A046196 A123918 A044577

nonn,nice,more

njas