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 A079514 Second column of triangular array in A079513. 7
 1, 1, 3, 6, 22, 53, 211, 554, 2306, 6362, 27230, 77580, 338444, 986253, 4362627, 12927170, 57788170, 173452334, 781825066, 2370742868, 10757497972, 32892031042, 150073096238, 462030186916, 2117778107732, 6557906929108, 30176799215196, 93909078262808 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 D. Merlini, R. Sprugnoli and M. C. Verri, The tennis ball problem, J. Combin. Theory, A 99 (2002), 307-344 (Table A.2). FORMULA G.f.: 2*(1-sqrt(1-4*x))/(2+sqrt(1-4*x)+sqrt(1+4*x)). - Philippe Deléham, Feb 09 2014 MATHEMATICA 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 *) PROG (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 (Magma) m:=30; R:=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 (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 CROSSREFS Sequence in context: A295578 A054297 A325158 * A148624 A148625 A148626 Adjacent sequences: A079511 A079512 A079513 * A079515 A079516 A079517 KEYWORD nonn AUTHOR N. J. A. Sloane, Jan 22 2003 EXTENSIONS More terms from Philippe Deléham, Feb 09 2014 STATUS approved

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Last modified February 24 06:45 EST 2024. Contains 370294 sequences. (Running on oeis4.)