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 A079514 #16 Sep 08 2022 08:45:08
%S A079514 1,1,3,6,22,53,211,554,2306,6362,27230,77580,338444,986253,4362627,
%T A079514 12927170,57788170,173452334,781825066,2370742868,10757497972,
%U A079514 32892031042,150073096238,462030186916,2117778107732,6557906929108,30176799215196,93909078262808
%N A079514 Second column of triangular array in A079513.
%H A079514 G. C. Greubel, <a href="/A079514/b079514.txt">Table of n, a(n) for n = 1..1000</a>
%H A079514 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.2).
%F A079514 G.f.: 2*(1-sqrt(1-4*x))/(2+sqrt(1-4*x)+sqrt(1+4*x)). - _Philippe Deléham_, Feb 09 2014
%t A079514 Rest[CoefficientList[Series[2*(1-Sqrt[1-4*x])/(2+Sqrt[1-4*x] +Sqrt[1+ 4*x]), {x, 0, 30}], x]] (* _G. C. Greubel_, Jan 15 2019 *)
%o A079514 (PARI) my(x='x+O('x^30)); Vec(2*(1-sqrt(1-4*x))/(2+sqrt(1-4*x) +sqrt(1 +4*x))) \\ _G. C. Greubel_, Jan 15 2019
%o A079514 (Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); Coefficients(R!( 2*(1-Sqrt(1-4*x))/(2+Sqrt(1-4*x)+Sqrt(1+4*x)) )); // _G. C. Greubel_, Jan 15 2019
%o A079514 (Sage) a=(2*(1-sqrt(1-4*x))/(2+sqrt(1-4*x)+sqrt(1+4*x))).series(x, 30).coefficients(x, sparse=False); a[1:] # _G. C. Greubel_, Jan 15 2019
%K A079514 nonn
%O A079514 1,3
%A A079514 _N. J. A. Sloane_, Jan 22 2003
%E A079514 More terms from _Philippe Deléham_, Feb 09 2014