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 A066655 Number of partitions of n*(n-1)/2. 6
 1, 1, 3, 11, 42, 176, 792, 3718, 17977, 89134, 451276, 2323520, 12132164, 64112359, 342325709, 1844349560, 10015581680, 54770336324, 301384802048, 1667727404093, 9275102575355, 51820051838712, 290726957916112, 1637293969337171, 9253082936723602 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Number of partitions of the number of edges of the complete graph of order n, K_n. LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 FORMULA a(n) = p(n*(n-1)/2) = A000041(n*(n-1)/2). a(n) ~ exp(Pi*sqrt(n*(n-1)/3))/(2*sqrt(3)*n*(n - 1)). - Ilya Gutkovskiy, Jan 13 2017 a(n) ~ exp(Pi*(n - 1/2) / sqrt(3)) / (2*sqrt(3)*n^2). - Vaclav Kotesovec, May 17 2018 EXAMPLE a(4) = p(6) = 11. MATHEMATICA Table[PartitionsP[n(n-1)/2], {n, 1, 30}] PROG (MuPAD) combinat::partitions::count(binomial(n+2, n)) \$n=-1..40 // Zerinvary Lajos, Apr 16 2007 (PARI) a(n) = numbpart(n*(n-1)/2); \\ Michel Marcus, Dec 18 2017 CROSSREFS Cf. A000041, A000217, A007294, A104383. Cf. A173519. - Reinhard Zumkeller, Feb 20 2010 Sequence in context: A211854 A200212 A149070 * A302421 A118166 A277888 Adjacent sequences:  A066652 A066653 A066654 * A066656 A066657 A066658 KEYWORD nonn AUTHOR Roberto E. Martinez II, Jan 10 2002 EXTENSIONS More terms from Vladeta Jovovic, Jan 12 2002 Edited by Dean Hickerson, Jan 14 2002 STATUS approved

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Last modified August 6 15:50 EDT 2020. Contains 336255 sequences. (Running on oeis4.)