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Number of ways to place 2 non-attacking wazirs on an n X n toroidal board.
8

%I #14 Apr 10 2020 02:12:10

%S 0,2,18,88,250,558,1078,1888,3078,4750,7018,10008,13858,18718,24750,

%T 32128,41038,51678,64258,79000,96138,115918,138598,164448,193750,

%U 226798,263898,305368,351538,402750,459358,521728,590238,665278,747250,836568,933658,1038958

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

%C A wazir is a leaper [0,1].

%H V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, p.402

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

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

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

%K nonn

%O 1,2

%A _Vaclav Kotesovec_, Nov 28 2011