%I M5365 N2331 #18 Oct 19 2017 03:13:42
%S 97,139,151,199,211,331,433,541,547,601,607,631,751,787,937,1039,1063,
%T 1249,1321,1327,1381,1471,1483,1663,1693,1741,1747,1879,1999,2113,
%U 2143,2377,2437,2503,2521,2557,2593,2677,2797,2857,2887,3019,3121,3313,3331,3361
%N Primes p of the form 3k+1 such that sum_{x=1..p} cos(2*Pi*x^3/p) < -sqrt(p).
%D H. Hasse, Vorlesungen über Zahlentheorie. Springer-Verlag, NY, 1964, p. 482.
%D G. B. Mathews, Theory of Numbers, 2nd edition. Chelsea, NY, p. 228.
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H T. D. Noe, <a href="/A000923/b000923.txt">Table of n, a(n) for n = 1..1000</a>
%H D. R. Heath-Brown, <a href="http://eprints.maths.ox.ac.uk/158/01/kummer.pdf">Kummer's Conjecture for Cubic Gauss Sums</a>
%e 97 is here because the sum of cos(2*Pi*x^3/97) = -11.3259 < -sqrt(97).
%Y Cf. A000921, A000922, A002476.
%K nonn
%O 1,1
%A _N. J. A. Sloane_
%E Edited by _Don Reble_, May 26 2007