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A152518 1/36 of the number of permutations of 8 indistinguishable copies of 1..n with exactly 2 local maxima. 2
0, 7, 1290, 214713, 35450244, 5849546139, 965177888238, 159254380788525, 26276973131433672, 4335700569742873071, 715390594038180275346, 118039448016603095674977, 19476508922742491987034060, 3213623972252540268102877443, 530247955421669426384081722614 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (183,-3051,13365).

FORMULA

a(n) = (97*165^(n-1) - 97*9^(n-1) - 104*(n-1)*9^(n-1))/2028. - Andrew Howroyd, May 10 2020

From Colin Barker, Jul 18 2020: (Start)

G.f.: x^2*(7 + 9*x) / ((1 - 9*x)^2*(1 - 165*x)).

a(n) = 183*a(n-1) - 3051*a(n-2) + 13365*a(n-3) for n>3.

(End)

PROG

(PARI) a(n) = {(97*165^(n-1) - 97*9^(n-1) - 104*(n-1)*9^(n-1))/2028} \\ Andrew Howroyd, May 10 2020

(PARI) concat(0, Vec(x^2*(7 + 9*x) / ((1 - 9*x)^2*(1 - 165*x)) + O(x^17))) \\ Colin Barker, Jul 18 2020

CROSSREFS

Cf. A152494, A334773.

Sequence in context: A278178 A190266 A119181 * A210396 A289482 A214010

Adjacent sequences:  A152515 A152516 A152517 * A152519 A152520 A152521

KEYWORD

nonn,easy

AUTHOR

R. H. Hardin, Dec 06 2008

EXTENSIONS

Terms a(7) and beyond from Andrew Howroyd, May 10 2020

STATUS

approved

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Last modified March 6 19:25 EST 2021. Contains 341849 sequences. (Running on oeis4.)