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 A255907 Number of collections of nonempty multisets with a total of 2n objects of exactly n colors. 2
 1, 2, 23, 492, 15800, 693667, 39371078, 2780643510, 237625842970, 24048952078889, 2833749745048664, 383425910861623475, 58894162142705623291, 10170230140575830362828, 1958227054977871232165423, 417406876191416533261184253, 97882032782014459518083172751 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..200 FORMULA a(n) = A255903(2n,n). EXAMPLE a(0) = 1: {}. a(1) = 2: {{1},{1}}, {{1,1}}. a(2) = 23: {{1},{1},{1},{2}}, {{1},{1},{2},{2}}, {{1},{2},{2},{2}}, {{1},{1},{1,2}}, {{1},{1},{2,2}}, {{1},{2},{1,1}}, {{1},{2},{1,2}}, {{1},{2},{2,2}}, {{2},{2},{1,1}}, {{2},{2},{1,2}}, {{1,1},{1,2}}, {{1,1},{2,2}}, {{1,2},{1,2}}, {{1,2},{2,2}}, {{1},{1,1,2}}, {{1},{1,2,2}}, {{1},{2,2,2}}, {{2},{1,1,1}}, {{2},{1,1,2}}, {{2},{1,2,2}}, {{1,1,1,2}}, {{1,1,2,2}}, {{1,2,2,2}}. CROSSREFS Cf. A255903. Sequence in context: A233211 A134355 A187656 * A054260 A053160 A167416 Adjacent sequences:  A255904 A255905 A255906 * A255908 A255909 A255910 KEYWORD nonn AUTHOR Alois P. Heinz, Mar 10 2015 STATUS approved

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Last modified February 17 02:22 EST 2020. Contains 331976 sequences. (Running on oeis4.)