A180237 - OEIS

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A180237

Number of lexicographically ordered pairs of permutations of 0..2n-2 such that their sum mod 2n-1 is also a permutation of 0..2n-2

%I #3 Mar 31 2012 12:35:46

%S 1,12,960,337680,367597440,755465356800,3208061483827200,

%T 23775433137840384000

%N Number of lexicographically ordered pairs of permutations of 0..2n-2 such that their sum mod 2n-1 is also a permutation of 0..2n-2

%C Numbers for permutations of 0..2n-1 are zero.

%K nonn

%O 1,2

%A _R. H. Hardin_ Aug 18 2010