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A172232
Number of ways to place 6 nonattacking wazirs on a 6 X n board.
3
0, 2, 504, 10010, 78052, 368868, 1280832, 3612344, 8774380, 19049692, 37898664, 70311824, 123209012, 205885204, 330502992, 512631720, 771833276, 1132294540, 1623506488, 2280989952, 3147068036, 4271685188, 5713272928, 7539662232, 9829042572, 12670967612
OFFSET
1,2
COMMENTS
Wazir is a (fairy chess) leaper [0,1].
LINKS
FORMULA
a(n) = 2*(486*n^6 -5670*n^5 +30240*n^4 -95230*n^3 +187899*n^2 -220775*n +120540) / 15, n>=5.
G.f.: -2*x^2 * (3*x^9 -5*x^8 +100*x^7 +354*x^6 +2548*x^5 +7572*x^4 +9248*x^3 +3262*x^2 +245*x +1) / (x-1)^7. - Vaclav Kotesovec, Mar 25 2010
MATHEMATICA
CoefficientList[Series[- 2 x (3 x^9 - 5 x^8 + 100 x^7 + 354 x^6 + 2548 x^5 + 7572 x^4 + 9248 x^3 + 3262 x^2 + 245 x + 1) / (x - 1)^7, {x, 0, 50}], x] (* Vincenzo Librandi, May 28 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vaclav Kotesovec, Jan 29 2010
STATUS
approved