A086864 - OEIS

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A086864

a(n) = (n-1)*(n-2)*(n-3)*(3*n-10)*3^(n-5)/4.

0, 0, 0, 1, 30, 360, 2970, 19845, 115668, 612360, 3018060, 14073345, 62788770, 270208224, 1128426390, 4594307445, 18302828040, 71553216240, 275154640632, 1042806816225, 3901324324230, 14427539010360, 52801538445810, 191427950399301, 688082033693340

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OFFSET

1,5

REFERENCES

L. Ericson et al., Enumeration of tree properties..., Algorithms Review, 1 (1990), 119-124.

LINKS

Table of n, a(n) for n=1..25.

Index entries for linear recurrences with constant coefficients, signature (15,-90,270,-405,243).

FORMULA

G.f.: x^4*(15*x+1)/(1-3*x)^5 [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 26 2009]

a(1)=0, a(2)=0, a(3)=0, a(4)=1, a(5)=30, a(n)=15*a(n-1)-90*a(n-2)+ 270*a(n-3)- 405*a(n-4)+243*a(n-5). - Harvey P. Dale, May 15 2015

a(n) = A036217(n-4)+15*A036217(n-5). - R. J. Mathar, Apr 14 2018

MATHEMATICA

Table[((n-1)(n-2)(n-3)(3n-10)3^(n-5))/4, {n, 30}] (* or *) LinearRecurrence[ {15, -90, 270, -405, 243}, {0, 0, 0, 1, 30}, 30] (* Harvey P. Dale, May 15 2015 *)

CROSSREFS

Sequence in context: A222086 A008656 A179717 * A138441 A058837 A042748

Adjacent sequences: A086861 A086862 A086863 * A086865 A086866 A086867

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Sep 16 2003

EXTENSIONS

G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.

Definition clarified by Harvey P. Dale, May 15 2015

STATUS

approved