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 A254243 Number of ways to partition the multiset consisting of 3 copies each of 1, 2, ..., n into n sets of size 3. 3
 1, 1, 2, 10, 93, 1417, 32152, 1016489, 42737945, 2307295021, 155607773014 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS P. A. MacMahon, Combinations derived from m identical sets of n different letters and their connexion with general magic squares, Proc. London Math. Soc., 17 (1917), 25-41. See page 40 (but there is a typo). StackExchange, Number of Partitioning a deck with m cards in n types into n-element sets, January 2015. EXAMPLE a(1) = 1: 111. a(2) = 2: 111|222 and 112|122. a(3) = 10: 111|222|333, 111|223|233, 112|122|333, 112|123|233, 112|133|223, 113|122|233, 113|123|223, 113|133|222, 122|123|133, and 123|123|123. CROSSREFS Cf. A002135 (2 instead of 3), A254233 (n copies each of 1, 2, and 3). Column k=3 of A257463. Sequence in context: A063393 A260339 A205320 * A026025 A231375 A100622 Adjacent sequences:  A254240 A254241 A254242 * A254244 A254245 A254246 KEYWORD nonn,more AUTHOR Tatsuru Murai, Jan 27 2015 EXTENSIONS Name and example edited by Danny Rorabaugh, Apr 22 2015 a(6)-a(10) from Alois P. Heinz, Apr 22 2015 STATUS approved

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Last modified February 22 23:14 EST 2020. Contains 332157 sequences. (Running on oeis4.)