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 A014280 Number of trees on n nodes with 3 forbidden limbs of size 4, 5 and 6. 2
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified April 21 04:54 EDT 2024. Contains 371850 sequences. (Running on oeis4.)