2,1

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

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.

Sequence in context: A126631 A046150 A124131 this_sequence A046196 A123918 A044577

Adjacent sequences: A000442 A000443 A000444 this_sequence A000446 A000447 A000448

nonn,nice,more

N. J. A. Sloane (njas(AT)research.att.com).