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 A195591 Number of ways to place 3n nonattacking kings on a vertical cylinder 6 X 2n. 1
 16, 90, 344, 1082, 3036, 7918, 19648, 47058, 109796, 251126, 565512, 1257754, 2769196, 6046014, 13107536, 28246370, 60555636, 129237382, 274727320, 581960106, 1228931516, 2587886030, 5435818464, 11391730162, 23823647236, 49727668758, 103616086568 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Vertical cylinder: a chessboard where it is supposed that the columns 1 and 6 are in contact (number of columns = 6, number of rows = 2n). LINKS V. Kotesovec, Non-attacking chess pieces Index entries for linear recurrences with constant coefficients, signature (6,-13,12,-4). FORMULA Recurrence: a(n) = -4*a(n-4) + 12*a(n-3) - 13*a(n-2) + 6*a(n-1). G.f.: (1+10*x+7*x^2)/((x-1)^2*(2*x-1)^2). a(n) = (31*n - 65)*2^n + 18*n + 66. MATHEMATICA LinearRecurrence[{6, -13, 12, -4}, {16, 90, 344, 1082}, 30] (* Harvey P. Dale, Nov 15 2021 *) CROSSREFS Cf. A194645, A061594, A137432. Sequence in context: A119771 A055920 A055856 * A240292 A050406 A047674 Adjacent sequences:  A195588 A195589 A195590 * A195592 A195593 A195594 KEYWORD nonn AUTHOR Vaclav Kotesovec, Sep 21 2011 STATUS approved

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Last modified May 27 21:14 EDT 2022. Contains 354110 sequences. (Running on oeis4.)