A244284 Number of ways to place n nonattacking zebras on an n X n chessboard.

1, 6, 84, 1168, 20502, 525796, 18939708, 802444170, 38934305898, 2170312156170

Offset: 1

Author

Vaclav Kotesovec, Jun 25 2014

Keywords

• nonn
• hard
• more

Comments

Zebra is a (fairy chess) leaper [2,3].

Links

• V. Kotesovec, Non-attacking chess pieces, 6ed, 2013, p.363
• Wikipedia, Fairy chess piece

Crossrefs

Cf. A172137, A172138, A172139, A172140.

Cf. A201540, A201511, A201861, A201513.

Formula

a(n) ~ n^(2*n)/n! * exp(-9/2).