A201771 Number of ways to place 9 nonattacking kings on an n X n board.

0, 0, 0, 0, 1, 3600, 2882737, 229095676, 6655170642, 103395053720, 1051588999820, 7878155295948, 46838274976147, 232322652402464, 995789500001315, 3784235129731708, 12999197522073908, 40969826999523768, 119876498636101786, 328726265508168780, 851369417500529061

Offset

1,6

Links

Table of n, a(n) for n=1..21.

V. Kotesovec, Non-attacking chess pieces

Formula

Explicit formula (Vaclav Kotesovec, after values computed by Andrew Woods, Dec 04 2011): n^18/362880 - n^16/1120 + n^15/840 + 1559*n^14/12096 - 119*n^13/360 - 7681*n^12/720 + 479*n^11/12 + 9383677*n^10/17280 - 195031*n^9/72 - 24176483*n^8/1440 + 4447749*n^7/40 + 5032857271*n^6/18144 - 495178813*n^5/180 - 2551293629*n^4/2520 + 1588223225*n^3/42 - 11469403819*n^2/315 - 664490248*n/3 + 405670140, n>=8.

G.f.: x^5*(54764*x^21 - 805588*x^20 + 6061268*x^19 - 31485512*x^18 + 117971558*x^17 - 312791986*x^16 + 620038858*x^15 - 1193322246*x^14 + 2685590901*x^13 - 4918483903*x^12 + 3824558880*x^11 + 5110355848*x^10 - 13987162841*x^9 + 5213745395*x^8 + 15789867458*x^7 - 14255103822*x^6 - 13342741937*x^5 - 2791816301*x^4 - 174938304*x^3 - 2814508*x^2 - 3581*x - 1)/(x-1)^19.

Crossrefs

Cf. A061995, A061996, A061997, A061998, A172158, A193580, A194788, A201369.

Sequence in context: A364990 A250439 A027824 * A068291 A003838 A296907

Adjacent sequences: A201768 A201769 A201770 * A201772 A201773 A201774

Keyword

nonn

Author

Vaclav Kotesovec, Dec 04 2011

Status

approved