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A121137
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Number of labeled directed multigraphs (without loops) with n arcs and no vertex of degree 0.
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1
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1, 2, 27, 572, 16787, 631362, 28980861, 1570956872, 98212870233, 6956704585554, 550626446263423, 48163137319172436, 4613554511554200251, 480324019903607680066, 54004504167811544647161, 6521368218660772789452944
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OFFSET
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0,2
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LINKS
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MAPLE
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seq(sum(binomial(m*(m-1)+n-1, n)/2^(m+1), m=0..infinity), n=0..10);
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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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STATUS
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approved
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