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A019581 Place n distinguishable balls in n boxes (in n^n ways); let f(n,k) = number of ways that max in any box is k, for 1<=k<=n; sequence gives f(n,2). 0
0, 2, 18, 180, 2100, 28800, 458640, 8361360, 172141200, 3954484800, 100330876800, 2786980996800, 84133667217600, 2742770705875200, 96032990237184000, 3594185336405664000, 143193231131382432000 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

FORMULA

Sum n!^2 / ( 2^d (n-2d)! d! d! ), d=1..[ n/2 ].

CROSSREFS

Cf. A019576.

Sequence in context: A132306 A099044 A161122 * A183285 A129627 A138413

Adjacent sequences:  A019578 A019579 A019580 * A019582 A019583 A019584

KEYWORD

nonn,easy

AUTHOR

Lee Corbin (lcorbin(AT)tsoft.com), N. J. A. Sloane (njas(AT)research.att.com).

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Last modified February 14 19:37 EST 2012. Contains 205663 sequences.