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A186755
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Number of permutations of {1,2,...,n} having no increasing cycles. A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1)<b(2)<b(3)<... .
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11
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1, 0, 0, 1, 5, 23, 129, 894, 7202, 65085, 651263, 7161713, 85922825, 1116946192, 15637356864, 234562319757, 3753007054781, 63801128569995, 1148420035784849, 21819978138955622, 436399552962252082, 9164390639379582121, 201616594791853840063
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OFFSET
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0,5
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COMMENTS
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LINKS
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FORMULA
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E.g.f.: exp(1-exp(z))/(1-z).
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EXAMPLE
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a(4)=5 because we have (1432), (1342), (1423), (1243), and (1324).
a(5)=23 counts all cyclic permutations of {1,2,3,4,5}, except (12345).
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MAPLE
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g := exp(1-exp(z))/(1-z): gser := series(g, z = 0, 25): seq(factorial(n)*coeff(gser, z, n), n = 0 .. 22);
# second Maple program:
a:= proc(n) option remember; `if`(n=0, 1, add(
a(n-j)*binomial(n-1, j-1)*((j-1)!-1), j=1..n))
end:
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MATHEMATICA
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With[{nn=30}, CoefficientList[Series[Exp[1-Exp[x]]/(1-x), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 23 2016 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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