A014280 - OEIS

A014280

Number of trees on n nodes with 3 forbidden limbs of size 4, 5 and 6.

0, 1, 1, 2, 3, 6, 12, 28, 64, 152, 363, 883, 2165, 5375, 13439, 33885, 85960, 219398, 562768, 1450356, 3753054, 9748390, 25406262, 66419263, 174128256, 457690900, 1205900244, 3184274398, 8425557609, 22336457078, 59319973057

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..30.

T. Lu, The enumeration of trees with and without given limbs, Discr. Math., 154 (1996), 153-165, Example 7.

Index entries for sequences related to trees

FORMULA

G.f. (x-x^4-x^5-x^6+x^8+x^9+x^10-x^13)/[Product_{p>=1} (1-x^p)^a(p)], implicit form. - R. J. Mathar, Feb 27 2016

MATHEMATICA

nmax = 30; b = ConstantArray[0, nmax+1]; b[[1]] = 0; b[[2]] = 1; Do[b[[n+1]] = SeriesCoefficient[(x-x^4-x^5-x^6+x^8+x^9+x^10-x^13) / Product[(1 - x^p)^(b[[p+1]]), {p, 1, n-1}], {x, 0, n}], {n, 2, nmax}]; b (* Vaclav Kotesovec, Feb 28 2016 *)

CROSSREFS

Sequence in context: A104872 A006082 A122889 * A073431 A273873 A337717

Adjacent sequences: A014277 A014278 A014279 * A014281 A014282 A014283

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved