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A014276 Number of directed rooted trees on n nodes with forbidden limbs. 1
0, 1, 3, 15, 82, 495, 3144, 20874, 142766, 1000083, 7136463, 51699614, 379214625, 2810720045, 21018835670, 158389275075, 1201541422730, 9168456492986, 70324572634341, 541910543713685, 4193257236992896, 32568879336517050, 253822497160605899, 1984276479881989537, 15556238037968354214, 122274773948426045945 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..25.

T. Lu, The enumeration of trees with and without given limbs, Discr. Math., 154 (1996), 153-165, example 5.

Index entries for sequences related to rooted trees

FORMULA

G.f. (x-x^7-x^8+x^13)/[Product_{p>=1} (1-x^p)^(3*a(p)], in implicit form. - R. J. Mathar, Feb 26 2016

MATHEMATICA

nmax = 30; b = ConstantArray[0, nmax+1]; b[[1]] = 0; b[[2]] = 1; Do[b[[n+1]] = SeriesCoefficient[(x-x^7-x^8+x^13) / Product[(1 - x^p)^(3*b[[p+1]]), {p, 1, n-1}], {x, 0, n}], {n, 2, nmax}]; b (* Vaclav Kotesovec, Feb 28 2016 *)

CROSSREFS

Cf. A006964.

Sequence in context: A015680 A084208 A059271 * A006964 A203507 A192662

Adjacent sequences:  A014273 A014274 A014275 * A014277 A014278 A014279

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 18 17:45 EST 2019. Contains 329287 sequences. (Running on oeis4.)