A131082 - OEIS

%I #31 Apr 18 2024 09:47:03

%S 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,

%T 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,

%U 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

%N Periodic sequence (15, 11, 5, 1, 1, 5, 11, 15).

%C Fifth column of triangular array T defined in A131074.

%C Simple continued fraction of (1728521 + sqrt(3040737300437))/230114 = 15.0894426240... - _R. J. Mathar_, Mar 08 2012

%H Antti Karttunen, <a href="/A131082/b131082.txt">Table of n, a(n) for n = 1..8192</a>

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,-1,1).

%F a(n) = a(n-8).

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

%t 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 *)

%o (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))), ","))}

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

%o (Scheme) (define (A131082 n) (list-ref '(15 11 5 1 1 5 11 15) (modulo (- n 1) 8))) ;; _Antti Karttunen_, Aug 10 2017

%Y Cf. A131029, A131074.

%K nonn,easy

%O 1,1

%A _Klaus Brockhaus_, following a suggestion of _Paul Curtz_, Jun 14 2007