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A159710 Number of permutations of 1..n arranged in a circle with exactly 2 local maxima. 2
0, 0, 0, 0, 8, 80, 528, 2912, 14592, 69120, 316160, 1413632, 6223872, 27103232, 117067776, 502456320, 2145517568, 9122349056, 38644678656, 163186343936, 687144960000, 2886107922432, 12094385684480, 50577004298240, 211105074905088, 879606785638400 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (14,-76,200,-256,128).

FORMULA

G.f.: -8*(2*x^2-4*x+1)*x^4 / ((4*x-1)^2*(2*x-1)^3). - Maksym Voznyy (voznyy(AT)mail.ru), Jul 26 2009

a(n) = 2^(-5+n)*(4+2^n-4*n)*n for n>1. - Colin Barker, Oct 26 2015

MATHEMATICA

LinearRecurrence[{14, -76, 200, -256, 128}, {0, 0, 0, 0, 8, 80, 528}, 30] (* Harvey P. Dale, Sep 23 2017 *)

Join[{0, 0}, Table[2^(-5+n)*(4+2^n-4*n)*n, {n, 2, 30}]] (* G. C. Greubel, Jun 02 2018 *)

PROG

(PARI) concat([0, 0, 0, 0], Vec(-8*(2*x^2-4*x+1)*x^4 / ((4*x-1)^2*(2*x -1)^3) + O(x^100))) \\ Altug Alkan, Oct 26 2015

(PARI) a(n) = if(n==1, 0, 2^(-5+n)*(4+2^n-4*n)*n) \\ Colin Barker, Oct 26 2015

(MAGMA) [0, 0] cat [2^(-5+n)*(4+2^n-4*n)*n: n in [2..30]]; // G. C. Greubel, Jun 02 2018

CROSSREFS

Column k=2 of A263789.

Sequence in context: A102698 A190019 A055346 * A271555 A203290 A100472

Adjacent sequences:  A159707 A159708 A159709 * A159711 A159712 A159713

KEYWORD

nonn,easy

AUTHOR

R. H. Hardin, Apr 20 2009

EXTENSIONS

More terms from Alois P. Heinz, Oct 26 2015

STATUS

approved

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Last modified November 22 03:35 EST 2019. Contains 329386 sequences. (Running on oeis4.)