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 A165639 #5 Jun 05 2016 18:02:58
%S A165639 1,7,-35,259,-1799,12607,-88235,617659,-4323599,30265207,-211856435,
%T A165639 1482995059,-10380965399,72666757807,-508667304635,3560671132459,
%U A165639 -24924697927199,174472885490407,-1221310198432835,8549171389029859
%N A165639 a(n)=(7/4)*(1+3*(-7)^(n-1)).
%H A165639 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-6,7).
%F A165639 a(n)=(-7)*a(n-1)+14 with a(0)=1. a(0)=1, a(1)=7, a(n)=7*a(n-2)-6*a(n-1). G.f.: (1+13x)/(1+6x-7x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*6^(n-k).
%t A165639 LinearRecurrence[{-6,7},{1,7},30] (* _Harvey P. Dale_, Jun 05 2016 *)
%K A165639 sign
%O A165639 0,2
%A A165639 _Philippe Deléham_, Sep 23 2009