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A143019
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Infinite square array read by antidiagonals: a(q,n) is the coefficient of z^n in the series expansion of C(z)^q/(1-4z)^(3/2), where C(z) = (1-sqrt(1-4z))/(2z) is the Catalan function (q,n = 0,1,2,...).
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0
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1, 1, 6, 1, 7, 30, 1, 8, 38, 140, 1, 9, 47, 187, 630, 1, 10, 57, 244, 874, 2772, 1, 11, 68, 312, 1186, 3958, 12012, 1, 12, 80, 392, 1578, 5536, 17548, 51480, 1, 13, 93, 485, 2063, 7599, 25147, 76627, 218790, 1, 14, 107, 592, 2655, 10254, 35401, 112028, 330818
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OFFSET
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0,3
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COMMENTS
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a(q,n) = a(q-1,n) + a(q+1,n-1).
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LINKS
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FORMULA
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a(q,n) = Sum_{i=0..n} 4^i*binomial(2n-2i+q, n-i).
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EXAMPLE
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Array starts:
1, 6, 30, 140, 630, ...
1, 7, 38, 187, 874, ...
1, 8, 47, 244, 1186, ...
1, 9, 57, 312, 1578, ...
...
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MAPLE
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a:=proc(q, n) options operator, arrow: sum(4^i*binomial(2*n-2*i+q, n-i), i= 0.. n) end proc: aa:=proc(q, n) options operator, arrow: a(q-1, n-1) end proc: matrix(10, 10, aa); # yields sequence in matrix form
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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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