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 A086984 Number of arrangements of n labeled balls in n labeled columns where only 1 column may have more than 1 ball. 2
 1, 6, 60, 696, 9120, 134640, 2227680, 41005440, 833172480, 18546796800, 449223667200, 11766674304000, 331501679308800, 9997170543360000, 321355745238528000, 10969253822951424000, 396269940892041216000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The difference between A000407 and A086984 is for example consider a(5). A000407 allows the 221 and 23 partitions, A086984 does not. LINKS FORMULA a(n)=n!+sum(i=2, n, binomial(n-1, n-i)*n*n!) EXAMPLE a(2)=6; .. .. -G -R R- G- RG GR -R -G G- R- PROG (PARI) a(n)=n!+sum(i=2, n, binomial(n-1, n-i)*n*n!) for (i=2, 20, print1(a(i)", ")) CROSSREFS Cf. A000407, A086985. Sequence in context: A228484 A232969 A232246 * A000894 A112117 A065944 Adjacent sequences:  A086981 A086982 A086983 * A086985 A086986 A086987 KEYWORD nonn AUTHOR Jon Perry, Jul 27 2003 STATUS approved

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Last modified February 19 22:38 EST 2019. Contains 320328 sequences. (Running on oeis4.)