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A228859
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Triangular array read by rows. T(n,k) is the number of labeled bipartite graphs on n nodes having exactly k connected components; n>=1, 1<=k<=n.
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1
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1, 1, 1, 3, 3, 1, 19, 15, 6, 1, 195, 125, 45, 10, 1, 3031, 1545, 480, 105, 15, 1, 67263, 27307, 7035, 1400, 210, 21, 1, 2086099, 668367, 140098, 24045, 3430, 378, 28, 1, 89224635, 22427001, 3746925, 536214, 68355, 7434, 630, 36, 1
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OFFSET
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1,4
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COMMENTS
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The Bell transform of A001832(n+1) (without column 0). For the definition of the Bell transform see A264428. - Peter Luschny, Jan 21 2016
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LINKS
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Table of n, a(n) for n=1..45.
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FORMULA
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E.g.f.: sqrt(A(x)^y) where A(x) is the e.g.f. for A047863.
Sum_{k=1..n} T(n,k)*2^k = A047863(n).
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EXAMPLE
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1,
1, 1,
3, 3, 1,
19, 15, 6, 1,
195, 125, 45, 10, 1,
3031, 1545, 480, 105, 15, 1,
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MATHEMATICA
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nn=9; f[x_]:=Sum[Sum[Binomial[n, k]2^(k(n-k)), {k, 0, n}]x^n/n!, {n, 0, nn}]; Map[Select[#, #>0&]&, Drop[Range[0, nn]!CoefficientList[Series[Exp[y Log[f[x]]/2], {x, 0, nn}], {x, y}], 1]]//Grid
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PROG
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(Sage) # uses[bell_matrix from A264428, A001832]
# Adds 1, 0, 0, 0, ... as column 0 to the triangle.
bell_matrix(lambda n: A001832(n+1), 8) # Peter Luschny, Jan 21 2016
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CROSSREFS
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Row sums are A047864.
Column 1 is A001832.
Cf. A047863.
Sequence in context: A108391 A111840 A174031 * A259876 A276402 A318110
Adjacent sequences: A228856 A228857 A228858 * A228860 A228861 A228862
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KEYWORD
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nonn,tabl
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AUTHOR
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Geoffrey Critzer, Sep 05 2013
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STATUS
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approved
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