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A010688 Period 2: repeat (1,7). 10
1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Continued fraction of (7+ sqrt 77)/14. - R. J. Mathar, Nov 21 2011

LINKS

Table of n, a(n) for n=0..80.

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

FORMULA

a(n) = 4-3(-1)^n; G.f.: (1+7x)/((1+x)(1-x)); E.g.f.: 4*exp(x)-3*exp(-x). - Paul Barry, May 23 2003

a(n) = 7*(n mod 2)+(n+1) mod 2 - Paolo P. Lava, Oct 20 2006

a(n) = 7^n mod 8. - Vincenzo Librandi, Feb 07 2011

MATHEMATICA

PadRight[{}, 120, {1, 7}] (* Harvey P. Dale, Mar 21 2018 *)

PROG

(Sage) [power_mod(7, n, 8)for n in xrange(0, 92)] # Zerinvary Lajos, Nov 03 2009

(MAGMA) &cat[[1, 7]^^50]; // Vincenzo Librandi, Feb 07 2011 - Jul 23 2016

(PARI) a(n)=n%2*6+1 \\ Charles R Greathouse IV, Jun 11 2015

CROSSREFS

Sequence in context: A191562 A296472 A171544 * A176415 A317846 A198219

Adjacent sequences:  A010685 A010686 A010687 * A010689 A010690 A010691

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Corrected formula . - Philippe Deléham, Oct 30 2008

STATUS

approved

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Last modified July 18 15:44 EDT 2019. Contains 325144 sequences. (Running on oeis4.)