A187240 Number of ways to place 8 nonattacking bishops on an n X n board.

0, 0, 0, 0, 32, 12944, 867328, 22522960, 328097824, 3209594096, 23460698496, 137045115696, 670158151296, 2835083100640, 10634260782464, 36033282628832, 111923478184128, 322412415716896, 869530617762304, 2212626780591008, 5346773160475488, 12336574243905648, 27303885052866048

Offset

1,5

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Christopher R. H. Hanusa, T Zaslavsky, S Chaiken, A q-Queens Problem. IV. Queens, Bishops, Nightriders (and Rooks), arXiv preprint arXiv:1609.00853, a12016

V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)

E. Weisstein, Bishops Problem, MathWorld

Formula

a(n) = n^16/40320 - n^15/1080 + 7n^14/432 - 1153n^13/6480 + 53951n^12/38880 - 187277n^11/22680 + 106928053n^10/2721600 - 13957093n^9/90720 + 182160427n^8/362880 - 8821499n^7/6480 + 1176831457n^6/388800 - 490477369n^5/90720 + 8235592409n^4/1088640 - 726205757n^3/90720 + 1815275047n^2/302400 - 7953419n/2880 + 8491/16 + (-n^10/960 + 5n^9/144 - 307n^8/576 + 1793n^7/360 - 90571n^6/2880 + 201911n^5/1440 - 513865n^4/1152 + 477841n^3/480 - 4271471n^2/2880 + 1269721n/960 - 8491/16)*(-1)^n.

G.f.: -16x^5*(2520x^22 + 47160x^21 + 808884x^20 + 7825113x^19 + 54648810x^18 + 265795497x^17 + 965510650x^16 + 2638742416x^15 + 5598377728x^14 + 9280070520x^13 + 12189441400x^12 + 12689244954x^11 + 10499675700x^10 + 6853251794x^9 + 3501200340x^8 + 1373620536x^7 + 404231224x^6 + 85610168x^5 + 12313860x^4 + 1085765x^3 + 49362x^2 + 797x + 2)/((x-1)^17*(x+1)^11).

a(8) = A002465(8).

Mathematica

CoefficientList[Series[- 16 x^4 (2520 x^22 + 47160 x^21 + 808884 x^20 + 7825113 x^19 + 54648810 x^18 + 265795497 x^17 + 965510650 x^16 + 2638742416 x^15 + 5598377728 x^14 + 9280070520 x^13 + 12189441400 x^12 + 12689244954 x^11 + 10499675700 x^10 + 6853251794 x^9 + 3501200340 x^8 + 1373620536 x^7 + 404231224 x^6 + 85610168 x^5 + 12313860 x^4 + 1085765 x^3 + 49362 x^2 + 797 x + 2) / ((x - 1)^17 (x + 1)^11), {x, 0, 50}], x] (* Vincenzo Librandi, Jun 02 2013 *)

Crossrefs

Cf. A172123, A172124, A172127, A172129, A176886, A187239.

Sequence in context: A214387 A069444 A280100 * A062315 A221254 A159384

Adjacent sequences: A187237 A187238 A187239 * A187241 A187242 A187243

Keyword

nonn,easy

Author

Vaclav Kotesovec, Mar 07 2011

Status

approved