This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A120775 #36 Oct 10 2024 07:25:07
%S A120775 1,6,23,100,421,1786,7563,32040,135721,574926,2435423,10316620,
%T A120775 43701901,185124226,784198803,3321919440,14071876561,59609425686,
%U A120775 252509579303,1069647742900,4531100550901,19194049946506,81307300336923,344423251294200,1459000305513721
%N A120775 a(n) = 3*a(n-1) + 5*a(n-2) + a(n-3).
%H A120775 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,5,1).
%F A120775 a(n) = 3*a(n-1) + 5*a(n-2) + a(n-3).
%F A120775 G.f.: -x*(1+3*x) / ( (1+x)*(x^2+4*x-1) ). a(n) + a(n+1) = A048876(n). - _R. J. Mathar_, Oct 22 2013
%F A120775 a(n) = (Lucas(3n-1) + (-1)^n)/2. - _Greg Dresden_, Oct 09 2020
%t A120775 LinearRecurrence[{3,5,1},{1,6,23},25] (* _James C. McMahon_, Oct 09 2024 *)
%Y A120775 Cf. A120758, A120757.
%K A120775 nonn,easy
%O A120775 1,2
%A A120775 _Gary W. Adamson_ and _Roger L. Bagula_, Jul 04 2006
%E A120775 Edited by _N. J. A. Sloane_, Dec 03 2006
%E A120775 a(24)-a(25) from _James C. McMahon_, Oct 09 2024