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!)
A065530 If n is odd then a(n) = n, else a(n) = n*(n+2). 3

%I #23 Feb 22 2024 09:04:00

%S 0,1,8,3,24,5,48,7,80,9,120,11,168,13,224,15,288,17,360,19,440,21,528,

%T 23,624,25,728,27,840,29,960,31,1088,33,1224,35,1368,37,1520,39,1680,

%U 41,1848,43,2024,45,2208,47,2400,49,2600,51,2808,53,3024,55,3248,57

%N If n is odd then a(n) = n, else a(n) = n*(n+2).

%C Order of Fibonacci group F(n+1,2) (0 means group is infinite). - _N. J. A. Sloane_, Dec 30 2011

%D D. L. Johnson, Presentation of Groups, Cambridge, 1976, p. 182.

%D Thomas, Richard M., The Fibonacci groups revisited, in Groups - St. Andrews 1989, Vol. 2, 445-454, London Math. Soc. Lecture Note Ser., 160, Cambridge Univ. Press, Cambridge, 1991.

%H Harry J. Smith, <a href="/A065530/b065530.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,3,0,-3,0,1).

%F O.g.f.: (x+8x^2-x^5)/(1-x^2)^3. - _Len Smiley_, Dec 04 2001

%F a(n) = 3*a(n-2)-3*a(n-4)+a(n-6) for n>5. - _Colin Barker_, May 02 2015

%t Array[If[OddQ[#], #, #*(#+2)] &, 100, 0] (* _Paolo Xausa_, Feb 22 2024 *)

%o (PARI) { for (n=0, 1000, if (n%2, a=n, a=n*(n + 2)); write("b065530.txt", n, " ", a) ) } \\ _Harry J. Smith_, Oct 20 2009

%o (PARI) concat(0, Vec(x*(x^4-8*x-1)/((x-1)^3*(x+1)^3) + O(x^100))) \\ _Colin Barker_, May 02 2015

%Y A column of A202624.

%K easy,nonn

%O 0,3

%A _George E. Antoniou_, Dec 02 2001

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 15:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)