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 A274081 Number of unrooted labeled trees on 3n+2 nodes with node degree either one or four. 2
 1, 5, 560, 277200, 369969600, 1040623584000, 5318844410880000, 44743448895425280000, 577102758498249984000000, 10821132329283106871040000000, 283002122589833107696435200000000, 9986037506585076241055342592000000000, 462684151212030123561950840428953600000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS There are no unrooted labeled trees on 3n or 3n+1 nodes with node degree either one or four. LINKS Math.Stackexchange.com, Marko Riedel et al., Number of labeled trees MAPLE seq(binomial(3*n+2, n)*(3*n)!/(3!^n), n=0..16); MATHEMATICA Table[Binomial[3*n+2, n]*(3*n)!/(3!)^n, {n, 0, 10}] (* G. C. Greubel, Jun 09 2016 *) CROSSREFS Cf. A274056, A000272. Sequence in context: A112900 A259463 A241802 * A153404 A297821 A297991 Adjacent sequences:  A274078 A274079 A274080 * A274082 A274083 A274084 KEYWORD nonn AUTHOR Marko Riedel, Jun 09 2016 STATUS approved

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Last modified May 6 01:03 EDT 2021. Contains 343579 sequences. (Running on oeis4.)