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

Offset: 0

Author

Stuart M. Ellerstein (ellerstein(AT)aol.com), Apr 01 2000

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A070430, A070431.

Programs

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 *)
PowerMod[Range[0,120],2,7] (* or *) PadRight[{},120,{0,1,4,2,2,4,1}] (* Harvey P. Dale, Sep 01 2017 *)

PARI

a(n)=n^2%7 \\ Charles R Greathouse IV, Jun 11 2015

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

Extensions

More terms from James Sellers, Apr 08 2000