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 A165638 #5 Jan 07 2016 16:48:23
%S A165638 1,6,-24,156,-924,5556,-33324,199956,-1199724,7198356,-43190124,
%T A165638 259140756,-1554844524,9329067156,-55974402924,335846417556,
%U A165638 -2015078505324,12090471031956,-72542826191724,435256957150356
%N A165638 a(n)=(6/7)*(2+5*(-6)^(n-1)).
%H A165638 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-5,6).
%F A165638 a(n)=(-6)*a(n-1)+12 with a(0)=1. a(0)=1, a(1)=6, a(n)=6*a(n-2)-5*a(n-1). G.f.: (1+11x)/(1+5x-6x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*5^(n-k).
%t A165638 LinearRecurrence[{-5,6},{1,6},20] (* _Harvey P. Dale_, Jan 07 2016 *)
%K A165638 sign
%O A165638 0,2
%A A165638 _Philippe Deléham_, Sep 23 2009