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A010710 Period 2: repeat (4,5). 9
4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Continued fraction of 2 + 2*sqrt(30)/5. - R. J. Mathar, Nov 21 2011

Decimal expansion for 5/11. - Franklin T. Adams-Watters, Jan 25 2019

LINKS

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

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

FORMULA

a(n) = -(1/2)*(-1)^n + 9/2 = 5*(n mod 2) + 4*((n+1) mod 2). - Paolo P. Lava, Oct 20 2006

G.f.: (4+5*x)/(1-x^2). - Jaume Oliver Lafont, Mar 20 2009

a(n) = floor(9*(n+1)/2) - floor(9*n/2). - Hailey R. Olafson, Jul 17 2014

a(n) = 4 + (n mod 2). - Kritsada Moomuang, Sep 06 2018

MATHEMATICA

From Stefano Spezia, Sep 07 2018: (Start)

a[n_]:=-(1/2)*(-1)^n + 9/2; Array[a, 50, {0, 49}]

a[n_]:=Floor[9*(n+1)/2] - Floor[9*n/2]; Array[a, 50, {0, 49}]

a[n_]:= 4 + Mod[n, 2]; Array[a, 50, {0, 49}]

LinearRecurrence[{0, 1}, {4, 5}, 50]

CoefficientList[Series[(4+5*x)/(1-x^2), {x, 0, 50}], x]

(End)

PROG

(PARI) a(n)=4+n%2 \\ Jaume Oliver Lafont, Mar 20 2009

(PARI) a(n) = my(v=[4, 5]); v[n%2+1] \\ Felix Fröhlich, Sep 06 2018

(PARI) Vec((4+5*x)/(1-x^2) + O(x^100)) \\ Felix Fröhlich, Sep 06 2018

(PARI) contfrac(2+2*sqrt(30)/5) \\ Felix Fröhlich, Sep 06 2018

CROSSREFS

Sequence in context: A063694 A242624 A068901 * A021026 A126128 A046565

Adjacent sequences:  A010707 A010708 A010709 * A010711 A010712 A010713

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified July 19 12:35 EDT 2019. Contains 325159 sequences. (Running on oeis4.)