The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A172517 Number of ways to place 2 nonattacking queens on an n X n toroidal board. 9
 0, 0, 0, 32, 100, 288, 588, 1152, 1944, 3200, 4840, 7200, 10140, 14112, 18900, 25088, 32368, 41472, 51984, 64800, 79380, 96800, 116380, 139392, 165000, 194688, 227448, 264992, 306124, 352800, 403620, 460800, 522720, 591872, 666400, 749088, 837828 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (2,2,-6,0,6,-2,-2,1). FORMULA a(n) = n^2*(n-2)^2/2 if n is even and a(n) = n^2*(n-1)(n-3)/2 if n is odd. G.f.: -4*x^4*(x^3+6*x^2+9*x+8) / ((x-1)^5*(x+1)^3). - Colin Barker, Jan 09 2013 a(n) = 2*a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-5)-2*a(n-6)-2*a(n-7)+a(n-8). - Wesley Ivan Hurt, May 28 2021 MATHEMATICA CoefficientList[Series[- 4 x^3 (x^3 + 6 x^2 + 9 x + 8) / ((x - 1)^5 (x + 1)^3), {x, 0, 50}], x] (* Vincenzo Librandi, May 29 2013 *) LinearRecurrence[{2, 2, -6, 0, 6, -2, -2, 1}, {0, 0, 0, 32, 100, 288, 588, 1152}, 40] (* Harvey P. Dale, Sep 22 2015 *) CROSSREFS Cf. A007705, A036464. Sequence in context: A192293 A188862 A228686 * A194645 A134845 A167982 Adjacent sequences:  A172514 A172515 A172516 * A172518 A172519 A172520 KEYWORD nonn,nice,easy AUTHOR Vaclav Kotesovec, Feb 05 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 28 15:04 EDT 2022. Contains 354115 sequences. (Running on oeis4.)