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 A124722 #6 Nov 04 2020 12:13:08
%S A124722 2,9,40,137,448,1336,3840,10540,28160,73168,186368,465808,1146880,
%T A124722 2785024,6684672,15875520,37355520,87161600,201850880,464254208,
%U A124722 1061158912,2411718656,5452595200,12268325888,27481079808,61303918592
%N A124722 Number of ternary Lyndon words with exactly four 1's.
%H A124722 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (8,-20,0,76,-96,-32,128,-64).
%F A124722 G.f.: x^5*(2-3*x)*(1-x)^2/(1 - 2*x^2)^2/(1 - 2*x)^4 = (1/(1-2*x)^4-1/(1-2*x^2)^2)/4
%e A124722 a(6) = 9 because 111122, 111212, 111123, 111213, 112113, 111132, 111312, 111133, 111313 are all ternary Lyndon words with four 1's
%t A124722 LinearRecurrence[{8,-20,0,76,-96,-32,128,-64},{2,9,40,137,448,1336,3840,10540},40] (* _Harvey P. Dale_, Nov 04 2020 *)
%Y A124722 Cf. A051168, A027376, A124720, A124721, A124723.
%K A124722 nonn,easy
%O A124722 5,1
%A A124722 _Mike Zabrocki_, Nov 05 2006