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 A083594 #26 Aug 24 2024 05:54:18
%S A083594 1,5,-3,13,-19,45,-83,173,-339,685,-1363,2733,-5459,10925,-21843,
%T A083594 43693,-87379,174765,-349523,699053,-1398099,2796205,-5592403,
%U A083594 11184813,-22369619,44739245,-89478483,178956973,-357913939,715827885,-1431655763,2863311533,-5726623059
%N A083594 a(n) = (7 - 4*(-2)^n)/3.
%C A083594 Also generalized k-bonacci sequence a(n)=2*a(n-2)-a(n-1). - Philippe LALLOUET (philip.lallouet(AT)wanadoo.fr), Jun 30 2007
%H A083594 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-1,2).
%F A083594 G.f.: (1+6*x)/((1-x)*(1+2*x)).
%F A083594 E.g.f.: (7*exp(x)-4*exp(-2*x))/3.
%t A083594 (7-4(-2)^Range[0,40])/3 (* or *) LinearRecurrence[{-1,2},{1,5},40] (* _Harvey P. Dale_, Feb 25 2012 *)
%Y A083594 Cf. A083595.
%K A083594 easy,sign
%O A083594 0,2
%A A083594 _Paul Barry_, May 02 2003