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A283753
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Irregular triangular array read by rows: T(n,k) is the number of non-isomorphic unlabeled weakly connected digraphs on n nodes and with k arcs.
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3
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1, 1, 1, 3, 4, 4, 1, 1, 8, 22, 37, 47, 38, 27, 13, 5, 1, 1, 27, 108, 326, 667, 1127, 1477, 1665, 1489, 1154, 707, 379, 154, 61, 16, 5, 1, 1, 91, 582, 2432, 7694, 19646, 42148, 77305, 122953, 170315, 206982, 220768, 207301, 171008, 124110, 78813, 43862, 21209, 8951, 3242, 1043, 288, 76, 17, 5, 1, 1, 350, 3024, 17314, 74676, 266364, 808620, 2144407
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OFFSET
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1,4
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COMMENTS
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The range for the subindex k is from n-1 to n(n-1).
Obtained from A054733 by removing leading zeros.
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REFERENCES
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E. Palmer and F. Harary, Graphical Enumeration, Academic Press, 1973.
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LINKS
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EXAMPLE
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First rows are:
1;
1, 1;
3, 4, 4, 1, 1;
8, 22, 37, 47, 38, 27, 13, 5, 1, 1;
27, 108, 326, 667, 1127, 1477, 1665, 1489, 1154, 707, 379, ...
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PROG
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(PARI) \\ See A054733 for G, InvEulerMTS.
row(n)={Vecrev(polcoef(InvEulerMTS(sum(i=0, n, G(i, y)*x^i, O(x*x^n))), n)/y^(n-1))}
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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