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 A005777 Rook polynomials. (Formerly M3544) 1
 1, 4, 18, 96, 265, 672, 1617, 3776, 8577, 19080, 41745, 90048, 191945, 404992, 846945, 1757440, 3621697, 7417800, 15109313, 30623520, 61788489, 124158496, 248549937, 495852480, 986076225, 1955203016, 3866245425, 7625813888, 15005718153 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Table of n, a(n) for n=1..29. Earl Glen Whitehead, Jr., Four-discordant permutations, J. Austral. Math. Soc. Ser. A 28 (1979), no. 3, 369-377. FORMULA Conjecture: G.f.: x + 4*x^2 - 15*x^3 + x^3*((33 - 69*x + 16*x^2 - 14*x^3 + 82*x^4 - 8*x^5 - 20*x^6 - 38*x^7 + 9*x^8 + 9*x^9 + 8*x^10) / ((1 - x)^2 * (1 - x - x^2 - x^3)^3)). - Vaclav Kotesovec, Aug 27 2016 CROSSREFS A diagonal of A259985. Sequence in context: A370344 A081103 A243325 * A180567 A152392 A001563 Adjacent sequences: A005774 A005775 A005776 * A005778 A005779 A005780 KEYWORD nonn AUTHOR N. J. A. Sloane. EXTENSIONS More terms from Sean A. Irvine, Aug 27 2016 STATUS approved

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Last modified February 23 17:43 EST 2024. Contains 370283 sequences. (Running on oeis4.)