login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A131082 Periodic sequence (15, 11, 5, 1, 1, 5, 11, 15). 7
15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1, 1, 5, 11, 15, 15, 11, 5, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Fifth column of triangular array T defined in A131074.

Simple continued fraction of (1728521 + sqrt(3040737300437))/230114 = 15.0894426240... - R. J. Mathar, Mar 08 2012

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..8192

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

FORMULA

a(1) = a(8) = 15, a(2) = a(7) = 11, a(3) = a(6) = 5, a(4) = a(5) = 1; for n > 8, a(n) = a(n-8).

G.f.: (15 - 4*x - 6*x^2 - 4*x^3 + 15*x^4)/((1-x)*(1+x^4)).

a(n) = (1/28)*{8*(n mod 8) - 6*((n+1) mod 8) - 13*((n+2) mod 8) - 6*((n+3) mod 8) + 8*((n+4) mod 8) + 22*((n+5) mod 8) + 29*((n+6) mod 8) + 22*((n+7) mod 8)), with n >= 0. - Paolo P. Lava, Jun 19 2007

MATHEMATICA

PadRight[{}, 100, {15, 11, 5, 1, 1, 5, 11, 15}] (* or *) LinearRecurrence[ {1, 0, 0, -1, 1}, {15, 11, 5, 1, 1}, 100] (* Harvey P. Dale, Feb 01 2015 *)

PROG

(PARI) {m=84; for(n=1, m, r=(n-1)%8; print1(if(r==0||r==7, 15, if(r==1||r==6, 11, if(r==2||r==5, 5, 1))), ", "))}

(MAGMA) m:=84; [ [15, 11, 5, 1, 1, 5, 11, 15][(n-1) mod 8 + 1]: n in [1..m] ];

(Scheme) (define (A131082 n) (list-ref '(15 11 5 1 1 5 11 15) (modulo (- n 1) 8))) ;; Antti Karttunen, Aug 10 2017

CROSSREFS

Cf. A131029, A131074.

Sequence in context: A013449 A013461 A013430 * A296818 A097953 A200522

Adjacent sequences:  A131079 A131080 A131081 * A131083 A131084 A131085

KEYWORD

nonn,easy

AUTHOR

Klaus Brockhaus, following a suggestion of Paul Curtz, Jun 14 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 23 13:20 EST 2022. Contains 350511 sequences. (Running on oeis4.)