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A000268
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E.g.f.: -log(1+log(1+log(1-x))).
(Formerly M3003 N1218)
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12
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1, 3, 15, 105, 947, 10472, 137337, 2085605, 36017472, 697407850, 14969626900, 352877606716, 9064191508018, 252024567201300, 7542036496650006, 241721880399970938, 8261159383595659128, 299916384730043070880, 11526945327529620432872, 467583770376898192016104
(list;
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listen;
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OFFSET
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1,2
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REFERENCES
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J. Ginsburg, Iterated exponentials, Scripta Math., 11 (1945), 340-353.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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a(n) = sum((m-1)!*(-1)^(n+m)*sum(stirling1(n, k)*stirling1(k, m), k,m,n), m,1,n), n>0. - Vladimir Kruchinin, Sep 14 2010
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MATHEMATICA
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max = 20; CoefficientList[-Log[1 + Log[1 + Log[1 - x]]]/x + O[x]^max, x] * Range[max]! (* Jean-François Alcover, Feb 06 2016 *)
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PROG
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(PARI) a(n) = sum(m=1, n, (m-1)!*(-1)^(n+m)*sum(k=m, n, stirling(n, k, 1)*stirling(k, m, 1))); \\ Michel Marcus, Feb 06 2016
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CROSSREFS
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a(n)=|A039815(n, 1)| (first column of triangle).
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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