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A179425
Number of ways to place 5 nonattacking kings on an n X n toroidal board.
6
0, 0, 0, 0, 10, 14940, 229908, 1678336, 8155404, 30614620, 96011322, 263506752, 652150382, 1485650012, 3161648520, 6355083264, 12167739256, 22339050588, 39536586430, 67748508480, 112804636266, 183057635420, 290261282204, 450688785408, 686540794500, 1027700020828, 1513897376994, 2197363228480, 3146046781446, 4447496831580
OFFSET
1,5
FORMULA
Explicit formula: a(n) = 1/120*n^2*(n^8-90n^6+3155n^4-51450n^2+332544), n>=6.
G.f.: -2x^5*(260x^11 - 1932x^10 + 6567x^9 - 16223x^8 + 38507x^7 - 77869x^6 + 102208x^5 - 61576x^4 - 15301x^3 + 33059x^2 + 7415x + 5)/(x-1)^11.
MATHEMATICA
CoefficientList[Series[- 2 x^4 (260 x^11 - 1932 x^10 + 6567 x^9 - 16223 x^8 + 38507 x^7 - 77869 x^6 + 102208 x^5 - 61576 x^4 - 15301 x^3 + 33059 x^2 + 7415 x + 5) / (x - 1)^11, {x, 0, 50}], x] (* Vincenzo Librandi, Jun 01 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vaclav Kotesovec, Jan 07 2011
STATUS
approved