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A133413
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Half the number of ways of placing up to n^2 pawns on an n x n chessboard so that it balances at its midpoint.
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2
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1, 2, 24, 492, 202064, 100202536, 888531141152, 8548846756027594, 1400822035743239844640, 241149984205773848119833656, 691305758149247080625180837349904, 2048332087899166877612856148780183708362, 99840603982108483679316058344233421388081447648
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OFFSET
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1,2
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LINKS
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PROG
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(PARI) a(n) = {polcoef(polcoef(prod(j=1, n, prod(k=1, n, 1 + 'x^(2*k-n-1)*'y^(2*j-n-1) )), 0), 0)/2} \\ Andrew Howroyd, Jan 07 2023
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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