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 A014280 Number of trees on n nodes with 3 forbidden limbs of size 4, 5 and 6. 1

%I

%S 0,1,1,2,3,6,12,28,64,152,363,883,2165,5375,13439,33885,85960,219398,

%T 562768,1450356,3753054,9748390,25406262,66419263,174128256,457690900,

%U 1205900244,3184274398,8425557609,22336457078,59319973057

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

%H T. Lu, <a href="http://dx.doi.org/10.1016/0012-365X(95)00041-T">The enumeration of trees with and without given limbs</a>, Discr. Math., 154 (1996), 153-165, Example 7.

%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>

%F 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

%t 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 *)

%K nonn

%O 0,4

%A _N. J. A. Sloane_.

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Last modified August 23 22:45 EDT 2019. Contains 326254 sequences. (Running on oeis4.)