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A201240
Number of ways to place 6 non-attacking wazirs on an n X n toroidal board.
8
0, 0, 0, 56, 7100, 252792, 3378942, 26249184, 144455454, 625745100, 2271361422, 7192874328, 20427662398, 53065637212, 127956238350, 289628321664, 620834113614, 1269178026012, 2488676915070, 4702895069400, 8598589878606, 15261688799500, 26371002575326
OFFSET
1,4
COMMENTS
Wazir is a leaper [0,1].
FORMULA
a(n) = n^2*(n^10 - 75*n^8 + 2365*n^6 - 39285*n^4 + 345034*n^2 - 1288680)/720, n>=7.
G.f.: 2*x^4 * (6*x^15 - 103*x^14 + 873*x^13 - 4241*x^12 + 12757*x^11 - 26112*x^10 + 45344*x^9 - 90774*x^8 + 189180*x^7 - 293907*x^6 + 260273*x^5 - 25077*x^4 - 315215*x^3 - 82430*x^2 - 3186*x - 28)/(x-1)^13.
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Nov 28 2011
STATUS
approved