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 A086864 a(n) = (n-1)*(n-2)*(n-3)*(3*n-10)*3^(n-5)/4. 0
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified April 15 12:18 EDT 2024. Contains 371686 sequences. (Running on oeis4.)