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A141771
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Expansion of (1-sqrt(1-4*x))/(2*x) + 8*x^3/((sqrt(1-4*x))*(1+sqrt(1-4*x))^3).
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1
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1, 1, 2, 6, 19, 63, 216, 759, 2717, 9867, 36244, 134368, 501942, 1886966, 7131840, 27078705, 103221585, 394827315, 1514797020, 5827192140, 22469489130, 86825411010, 336145233840, 1303626531870, 5063559897474, 19695844095678, 76710709889576, 299125464317904
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OFFSET
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0,3
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LINKS
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FORMULA
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Conjecture: (n+1) *(n^2+5*n-12) *(n^3-5*n^2+38*n-250)*a(n) -2 *(2*n-3) *(n^2+7*n-6) *(n^3-5*n^2+38*n-250) *a(n-1)=0. - R. J. Mathar, Apr 30 2016
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MATHEMATICA
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a[n_] := Switch[n, 0, 1, 1, 1, _, CatalanNumber[n] + Binomial[2n-3, n-3]]; Table[a[n], {n, 0, 27}] (* Jean-François Alcover, Oct 06 2016, after R. J. Mathar *)
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PROG
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(PARI) x='x+O('x^40); Vec((1-sqrt(1-4*x))/(2*x) + 8*x^3/((sqrt(1-4*x))*(1+sqrt(1-4*x))^3)) \\ Michel Marcus, Oct 30 2015
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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