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

1, 12, 960, 337680, 367597440, 755465356800, 3208061483827200, 23775433137840384000

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..8.

Crossrefs

Sequence in context: A047802 A378779 A278705 * A079916 A204327 A370313

Adjacent sequences: A180234 A180235 A180236 * A180238 A180239 A180240

Keyword

nonn

Author

R. H. Hardin Aug 18 2010

Status

approved