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A133413
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.
2
1, 2, 24, 492, 202064, 100202536, 888531141152, 8548846756027594, 1400822035743239844640, 241149984205773848119833656, 691305758149247080625180837349904, 2048332087899166877612856148780183708362, 99840603982108483679316058344233421388081447648
OFFSET
1,2
PROG
(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
CROSSREFS
Sequence in context: A341958 A360975 A052712 * A012236 A186414 A359848
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 25 2007
EXTENSIONS
a(12)-a(13) from Andrew Howroyd, Jan 07 2023
STATUS
approved