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 A093834 #8 Jun 13 2015 00:51:20
%S A093834 1,3,13,55,229,943,3853,15655,63349,255583,1028893,4135255,16600069,
%T A093834 66577423,266841133,1068958855,4280618389,17136822463,68590336573,
%U A093834 274490486455,1098349366309,4394559726703,17581725691213,70337363118055
%N A093834 Expansion of (1-2x)^2/((1-3x)(1-4x)).
%C A093834 Binomial transform of A093833.
%H A093834 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (7,-12).
%F A093834 a(n)=4^n-3^n/3-0^n/3. a(n+1)=4^(n+1)-3^n, n>0.
%F A093834 a(0)=1, a(1)=3, a(2)=13, a(n)=7*a(n-1)-12*a(n-2) [From _Harvey P. Dale_, Dec 27 2011]
%t A093834 CoefficientList[Series[(1-2x)^2/((1-3x)(1-4x)),{x,0,30}],x] (* or *) Join[{1},LinearRecurrence[{7,-12},{3,13},30]] (* _Harvey P. Dale_, Dec 27 2011 *)
%Y A093834 Cf. A085350.
%K A093834 easy,nonn
%O A093834 0,2
%A A093834 _Paul Barry_, Apr 17 2004