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 A079517 #10 Jan 17 2019 03:10:30
%S A079517 1,21,301,4088,55354,756059,10442117,145803900,2056351566,29262470042,
%T A079517 419730456306,6062949606496,88127311401876,1288120149337735,
%U A079517 18922077118169717,279209456350438708,4136682188907493702,61513664658938124486,917795824360157700870
%N A079517 Coefficients related to tennis ball problem.
%H A079517 G. C. Greubel, <a href="/A079517/b079517.txt">Table of n, a(n) for n = 0..500</a>
%H A079517 D. Merlini, R. Sprugnoli and M. C. Verri, <a href="http://dx.doi.org/10.1006/jcta.2002.3273">The tennis ball problem</a>, J. Combin. Theory, A 99 (2002), 307-344. (Table A.3)
%F A079517 With c(t) = (1 - sqrt(1-4*t))/(2*t), d(t) = (1 -(1+2*t)*sqrt(1-4*t) -(1 - 2*t)*sqrt(1+4*t) + sqrt(1-16*t^2))/(4*t^2), and g(t, r) = d(t)*t^(r + 1)*c(t)^(r + 3) then the g.f. is given by the odd terms in the expansion of g(t,2) = 1*t^3 + 21*t^5 + 301*t^7 + 4088*t^9 + ... - _G. C. Greubel_, Jan 16 2019
%t A079517 c[t_]:= (1-Sqrt[1-4*t])/(2*t); d[t_]:= (1-(1+2*t)*Sqrt[1-4*t] -(1-2*t)*Sqrt[1+4*t] +Sqrt[1-16*t^2])/(4*t^2); g[t_, r_]:= d[t]*t^(r+1)*c[t]^(r+3); Drop[CoefficientList[Series[g[t, 2], {t, 0, 60}], t][[2 ;; ;; 2]], 1] (* _G. C. Greubel_, Jan 16 2019 *)
%Y A079517 Cf. A079513, A079514, A079515, A079516, A079518.
%K A079517 nonn
%O A079517 0,2
%A A079517 _N. J. A. Sloane_, Jan 22 2003
%E A079517 Terms a(5) onward added by _G. C. Greubel_, Jan 16 2019