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 A165625 #7 Jan 11 2022 12:43:05
%S A165625 1,5,-15,85,-415,2085,-10415,52085,-260415,1302085,-6510415,32552085,
%T A165625 -162760415,813802085,-4069010415,20345052085,-101725260415,
%U A165625 508626302085,-2543131510415,12715657552085,-63578287760415
%N A165625 a(n)=(5/3)*(1+2*(-5)^(n-1)).
%H A165625 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-4,5).
%F A165625 a(n)=(-5)*a(n-1)+10 with a(0)=1. a(0)=1, a(1)=5, a(n)=5*a(n-2)-4*a(n-1). G.f.: (1+9x)/(1+4x-5x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*4^(n-k).
%t A165625 LinearRecurrence[{-4,5},{1,5},30] (* _Harvey P. Dale_, Nov 28 2015 *)
%Y A165625 Cf. A083217, A084247, A165553, A165622
%K A165625 easy,sign
%O A165625 0,2
%A A165625 _Philippe Deléham_, Sep 22 2009