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 A166868 #10 May 28 2016 03:50:17
%S A166868 1,5,16,48,133,357,932,2392,6057,15189,37800,93520,230301,565045,
%T A166868 1382236,3373208,8216033,19980037,48525632,117730352,285384437,
%U A166868 691295429,1673567700,4049615640,9795168601,23684692085,57254031256
%N A166868 Convolution of Jacobsthal(n+2) and Pell(n+1).
%H A166868 G. C. Greubel, <a href="/A166868/b166868.txt">Table of n, a(n) for n = 0..1000</a>
%H A166868 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,1,-5,-2).
%F A166868 G.f.: (1+2*x)/((1-x-2x^2)*(1-2x-x^2)).
%F A166868 a(n) = Sum{k=0..n} A001045(k+2)*A000129(n-k+1).
%F A166868 a(n) = 3*a(n-1) + a*(n-2) - 5*a(n-3) - 2*a(n-4).
%t A166868 LinearRecurrence[{3, 1, -5, -2}, {1, 5, 16, 48}, 100] (* _G. C. Greubel_, May 27 2016 *)
%K A166868 easy,nonn
%O A166868 0,2
%A A166868 _Paul Barry_, Oct 22 2009