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%I #7 May 06 2020 16:32:40
%S 1,8,5904,2456909824,2179875344187129600
%N Number of n X n whirlpool permutations (see A334518).
%H D. E. Knuth, <a href="https://cs.stanford.edu/~knuth/papers/whirlpool.pdf">Whirlpool Permutations</a>, May 05 2020
%Y Cf. A000142 (1Xn), A261683 (2Xn), A334516 (3Xn), A334518 and A334519 (mXn).
%K nonn,more
%O 1,2
%A _N. J. A. Sloane_, May 06 2020