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!)
A168202 a(n) = 3*n - a(n-1) + 1 with n > 1, a(1)=5. 1

%I #27 Feb 23 2023 03:46:18

%S 5,2,8,5,11,8,14,11,17,14,20,17,23,20,26,23,29,26,32,29,35,32,38,35,

%T 41,38,44,41,47,44,50,47,53,50,56,53,59,56,62,59,65,62,68,65,71,68,74,

%U 71,77,74,80,77,83,80,86,83,89,86,92,89,95,92,98,95,101,98,104,101,107,104

%N a(n) = 3*n - a(n-1) + 1 with n > 1, a(1)=5.

%H Vincenzo Librandi, <a href="/A168202/b168202.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).

%F From _R. J. Mathar_, Nov 22 2009: (Start)

%F a(n) = a(n-1) + a(n-2) - a(n-3).

%F a(n) = (5 - 9*(-1)^n)/4 + 3*n/2.

%F G.f.: x*(5 - 3*x + x^2)/((1+x)*(x-1)^2). (End)

%F E.g.f.: (1/4)*(-9 + 4*exp(x) + (5 + 6*x)*exp(2*x))*exp(-x). - _G. C. Greubel_, Jul 15 2016

%F Sum_{n>=1} (-1)^n/a(n) = 1/2. - _Amiram Eldar_, Feb 23 2023

%t LinearRecurrence[{1, 1, -1}, {5, 2, 8}, 60] (* _Vincenzo Librandi_, Feb 28 2012 *)

%o (Magma) I:=[5, 2, 8]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..40]]; // _Vincenzo Librandi_, Feb 28 2012

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Nov 20 2009

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 29 08:01 EDT 2024. Contains 371265 sequences. (Running on oeis4.)