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 A245854 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 1. 2
 1, 2, 12, 68, 520, 4542, 46550, 540136, 7045020, 101865410, 1619046418, 28053492348, 526430246264, 10636085523910, 230214619661790, 5314695463338704, 130356558777712468, 3385311352838750538, 92797887464933030762, 2677623216872061223780, 81123642038690958720048 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 1..400 FORMULA E.g.f.: 1/(2-exp(x))-1/(2-exp(x)+x). a(n) = A000670(n) - A032032(n) = A245732(n,1) - A245732(n,2). MAPLE b:= proc(n, k) option remember; `if`(n=0, 1,       add(b(n-j, k)*binomial(n, j), j=k..n))     end: a:= n-> b(n, 1) -b(n, 2): seq(a(n), n=1..25); CROSSREFS Column k=1 of A245733. Cf. A000670, A032032, A245732. Sequence in context: A245997 A128103 A329789 * A078839 A243771 A026306 Adjacent sequences:  A245851 A245852 A245853 * A245855 A245856 A245857 KEYWORD nonn AUTHOR Alois P. Heinz, Aug 04 2014 STATUS approved

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Last modified June 23 11:29 EDT 2021. Contains 345397 sequences. (Running on oeis4.)