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A097146
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Total sum of maximum list sizes in all sets of lists of n-set, cf. A000262.
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3
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0, 1, 5, 31, 217, 1781, 16501, 172915, 1998641, 25468777, 352751941, 5292123431, 85297925065, 1472161501981, 27039872306357, 527253067633531, 10865963240550241, 236088078855319505, 5390956470528548101, 129102989125943058607, 3234053809095307670201, 84596120521251178630981, 2305894874979300173268085
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OFFSET
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0,3
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LINKS
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FORMULA
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E.g.f.: exp(x/(1-x))*Sum_{k>0} (1-exp(x^k/(x-1))).
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EXAMPLE
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For n=4 we have 73 sets of lists (cf. A000262): (1234) (24 ways), (123)(4) (6*4 ways), (12)(34) (3*4 ways), (12)(3)(4) (6*2 ways), (1)(2)(3)(4) (1 way); so a(4)= 24*4+24*3+12*2+12*2+1*1 = 217.
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MAPLE
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b:= proc(n, m) option remember; `if`(n=0, m, add(j!*
b(n-j, max(m, j))*binomial(n-1, j-1), j=1..n))
end:
a:= n-> b(n, 0):
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MATHEMATICA
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b[n_, m_] := b[n, m] = If[n == 0, m, Sum[j! b[n-j, Max[m, j]] Binomial[n-1, j-1], {j, 1, n}]];
a[n_] := b[n, 0];
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PROG
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(PARI)
N=50; x='x+O('x^N);
egf=exp(x/(1-x))*sum(k=1, N, (1-exp(x^k/(x-1))) );
Vec( serlaplace(egf) ) /* show terms */
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CROSSREFS
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KEYWORD
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easy,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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