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%I #14 Aug 26 2015 10:17:52
%S 0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,
%T 0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,
%U 2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0,0,2,6,5,6,2,0
%N n^2+n modulo 7.
%C Pronic residues (mod m) are analogous to quadratic residues.
%C Periodic with period 7.
%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 1).
%t Table[Mod[n^2+n,7],{n,0,120}] (* _Harvey P. Dale_, Aug 26 2012 *)
%t LinearRecurrence[{0, 0, 0, 0, 0, 0, 1},{0, 2, 6, 5, 6, 2, 0},105] (* _Ray Chandler_, Aug 26 2015 *)
%o (PARI) A053793(n)=[0, 2, 6, 5, 6, 2, 0][n%7+1] \\ - _M. F. Hasler_, Aug 27 2012
%K nonn,easy
%O 0,2
%A Stuart M. Ellerstein (ellerstein(AT)aol.com), Mar 27 2000
%E More terms from _James A. Sellers_, Apr 08 2000
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