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%I #6 Oct 13 2022 12:52:32
%S 1,1,2,102,56904,1926158520,4018159809614880,822978002850717919227120
%N Number of n X n tables where rows represent distinct permutations of { 1, 2, ..., n } and the column sums are equal, up to permutation of rows.
%F a(n) = the coefficient of (x1*...*xn)^(n*(n-1)/2) in Product(1 + x1^(n-1)*x2^(n-2)*...*xn^0), where the product is taken over all permutations of the variables x1, ..., xn.
%F a(n) = A357766(n) / n!.
%Y Cf. A356722, A356723, A356724, A356725, A357766, A357768.
%K hard,more,nonn
%O 1,3
%A _Max Alekseyev_, Oct 12 2022
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