A201236 Number of ways to place 2 non-attacking wazirs on an n X n toroidal board.

0, 2, 18, 88, 250, 558, 1078, 1888, 3078, 4750, 7018, 10008, 13858, 18718, 24750, 32128, 41038, 51678, 64258, 79000, 96138, 115918, 138598, 164448, 193750, 226798, 263898, 305368, 351538, 402750, 459358, 521728, 590238, 665278, 747250, 836568, 933658, 1038958

Offset: 1

Author

Vaclav Kotesovec, Nov 28 2011

Keywords

• nonn

Comments

A wazir is a leaper [0,1].

Links

• V. Kotesovec, Non-attacking chess pieces, 6ed, p.402

Crossrefs

Cf. A172225, A201237, A201238, A201239, A201240, A201241, A201242.

Formula

a(n) = n^2*(n^2-5)/2, n>=3.

G.f.: 2*x^2 * (2*x^5 - 9*x^4 + 15*x^3 - 9*x^2 - 4*x - 1)/(x-1)^5.