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 A254233 Number of ways to partition the multiset consisting of n copies each of 1, 2, and 3 into n sets of size 3. 3
 1, 1, 4, 10, 25, 49, 103, 184, 331, 554, 911, 1424, 2204, 3278, 4817, 6896, 9746, 13487, 18480, 24882, 33192, 43683, 56994, 73512, 94131, 119340, 150300, 187732, 233065, 287248, 352153, 428944, 519949, 626737, 752095, 897994, 1067924, 1264241, 1491155, 1751672 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 FORMULA G.f.: (x^12-x^11+x^10+3*x^9+5*x^8+x^7+4*x^6+x^5+5*x^4+3*x^3+x^2-x+1) / ((x^2+1)*(x^2-x+1)*(x^2+x+1)^3*(x+1)^4*(x-1)^8). - Alois P. Heinz, Apr 21 2015 EXAMPLE For n = 2, the set {1,1,2,2,3,3} can be partitioned into two sets in four ways: {{112},{233}}, {{113},{223}}, {{122},{133}}, and {{123},{123}}. CROSSREFS Cf. A002135, A254243. Column k=3 of A257462. Sequence in context: A266826 A111207 A298018 * A300760 A229916 A113412 Adjacent sequences:  A254230 A254231 A254232 * A254234 A254235 A254236 KEYWORD nonn,easy AUTHOR Tatsuru Murai, Jan 27 2015 EXTENSIONS Fixed definition and examples by Kellen Myers, Apr 21 2015 a(14)-a(39) from Alois P. Heinz, Apr 21 2015 STATUS approved

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Last modified October 1 04:06 EDT 2020. Contains 337441 sequences. (Running on oeis4.)