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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 Harvey P. Dale, Table of n, a(n) for n = 1..402 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- MATHEMATICA Table[n!+Sum[Binomial[n-1, n-k], {k, 2, n}]n n!, {n, 20}] (* Harvey P. Dale, Nov 29 2019 *) 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 18 03:44 EST 2020. Contains 332006 sequences. (Running on oeis4.)