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A177756 Number of ways to place 3 nonattacking bishops on an n X n toroidal board. 6
0, 0, 6, 128, 600, 2688, 7350, 19968, 42336, 89600, 163350, 297600, 490776, 809088, 1242150, 1906688, 2774400, 4036608, 5633766, 7862400, 10613400, 14326400, 18818646, 24718848, 31740000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

V. Kotesovec, Non-attacking chess pieces, 6ed, 2013

FORMULA

Explicit formula: 1/12*(n-2)^2*n^2*(2*n^2-4*n+5+3(-1)^n).

G.f.: -2*x^3*(3*x^8+58*x^7+160*x^6+518*x^5+442*x^4+518*x^3+160*x^2+58*x+3)/((x-1)^7*(x+1)^5).

MATHEMATICA

CoefficientList[Series[- 2 x^2 * (3 x^8 + 58 x^7 + 160 x^6 + 518 x^5 + 442 x^4 + 518 x^3 + 160 x^2 + 58 x + 3)/((x - 1)^7 * (x + 1) ^5), {x, 0, 1 50}], x] (* Vincenzo Librandi, May 31 2013 *)

CROSSREFS

Cf. A172124, A177755.

Sequence in context: A081623 A223210 A324093 * A089314 A111873 A348796

Adjacent sequences:  A177753 A177754 A177755 * A177757 A177758 A177759

KEYWORD

nonn,easy

AUTHOR

Vaclav Kotesovec, May 13 2010

STATUS

approved

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Last modified December 3 21:17 EST 2021. Contains 349468 sequences. (Running on oeis4.)