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A351764
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a(n) = [x^n] Product_{k=1..n} (1 + k*x)^n / (1 - k*x)^n.
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0
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1, 2, 72, 7848, 1728000, 641258850, 360403076376, 285818177146208, 304172586944446464, 418400927094822149970, 722587619114932445325000, 1530927286486636135080191736, 3904621941927926455303092180480, 11801667653769333351640692783069714
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) ~ exp(n + 1) * n^(2*n - 1/2) / sqrt(2*Pi).
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MATHEMATICA
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Table[SeriesCoefficient[Product[(1 + k*x)^n / (1 - k*x)^n, {k, 1, n}], {x, 0, n}], {n, 0, 20}]
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PROG
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(PARI) a(n) = my(x='x+O(x^(n+1))); polcoef(prod(k=1, n, (1+k*x)^n/ (1-k*x)^n), n); \\ Michel Marcus, Feb 19 2022
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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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