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 A202207 #13 Apr 10 2024 04:41:28
%S A202207 1,2,5,14,39,108,299,828,2293,6350,17585,48698,134859,373464,1034231,
%T A202207 2864088,7931497,21964634,60826493,168446342,466477167,1291811652,
%U A202207 3577404131,9906877908,27435041245,75975649958,210398786537
%N A202207 a(n) = 3*a(n-1) - a(n-2) + a(n-3) with a(0)=1, a(1)=2, a(2)=5.
%H A202207 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-1,1).
%F A202207 G.f.: (1-x)/(1-3*x+x^2-x^3).
%F A202207 a(n) = A200752(n+3) - A200752(n+2). - _R. J. Mathar_, Dec 15 2011
%o A202207 (PARI) my(x='x+O('x^40)); Vec((1-x)/(1-3*x+x^2-x^3)) \\ _Michel Marcus_, Apr 10 2024
%Y A202207 Cf. A200752.
%K A202207 easy,nonn
%O A202207 0,2
%A A202207 _Philippe Deléham_, Dec 14 2011