A070425 - OEIS

A070425

a(n) = 7^n mod 43.

1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36, 37, 1, 7, 6, 42, 36

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OFFSET

0,2

COMMENTS

Sequence is periodic with length 6. Since a(21) = 42 (or -1), 43 is prime in Z[sqrt(7)]. - Alonso del Arte, Oct 12 2012

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

FORMULA

From R. J. Mathar, Apr 20 2010: (Start)

a(n) = a(n - 1) - a(n - 3) + a(n - 4).

G..f: ( -1 - 6*x + x^2 - 37*x^3 ) / ( (x - 1)*(1 + x)*(x^2 - x + 1) ). (End)