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A053879

a(n) = n^2 mod 7.

0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1, 0, 1, 4, 2, 2, 4, 1

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..104.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,1).

FORMULA

Periodic with period 7.

G.f.: -x*(1+x)*(x^4 + 3*x^3 - x^2 + 3*x + 1) / ( (x-1)*(1 + x + x^2 + x^3 + x^4 + x^5 + x^6) ). - R. J. Mathar, Feb 24 2011

MATHEMATICA

Table[Mod[n^2, 7], {n, 0, 200}] (* Vladimir Joseph Stephan Orlovsky, Apr 21 2011 *)

LinearRecurrence[{0, 0, 0, 0, 0, 0, 1}, {0, 1, 4, 2, 2, 4, 1}, 105] (* Ray Chandler, Aug 26 2015 *)