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A256640
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Triangle read by rows: T(n,k) = Sum_{i=n-k..n} C(k-1,n-i)*C(i,n-k)*C(2*i,i)/(i+1).
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0
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1, 1, 1, 2, 4, 3, 5, 15, 19, 10, 14, 56, 99, 90, 36, 42, 210, 476, 603, 427, 137, 132, 792, 2190, 3536, 3507, 2032, 543, 429, 3003, 9801, 19185, 24251, 19800, 9702, 2219, 1430, 11440, 43043, 98890, 151295, 157716, 109520, 46472, 9285, 4862, 43758
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OFFSET
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0,4
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LINKS
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FORMULA
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G.f.: (1-sqrt(1-4*(x/(1-x)+y)))/(2*(x/(1-x)+y)).
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EXAMPLE
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1;
1, 1;
2, 4, 3;
5, 15, 19, 10;
14, 56, 99, 90, 36;
42, 210, 476, 603, 427, 137;
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MATHEMATICA
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T[n_, k_] := SeriesCoefficient[1-Sqrt[1-4*(x/(1-x)+y)]/(2*(x/(1-x)+y)), {x, 0, n}, {y, 0, k}]; Table[T[n-k, k], {n, 0, 9}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Apr 13 2015 *)
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PROG
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(Maxima)
T(n, m):=sum((binomial(m-1, n-i)*binomial(i, n-m)*binomial(2*i, i))/(i+1), i, n-m, n);
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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