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Search: id:A058875
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| A058875 |
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Triangle T(n,k) = C_n(k)/2^(k*(k-1)/2) where C_n(k) = number of k-colored labeled graphs with n nodes (n >= 1, 1<=k<=n). |
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| 1, 1, 1, 1, 6, 1, 1, 40, 24, 1, 1, 360, 640, 80, 1, 1, 4576, 24000, 7040, 240, 1, 1, 82656, 1367296, 878080, 62720, 672, 1, 1, 2122240, 122056704, 169967616, 23224320, 487424, 1792, 1, 1, 77366400, 17282252800, 53247344640, 13440516096
(list; table; graph; listen)
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OFFSET
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1,5
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REFERENCES
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F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 18, Table 1.5.1.
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FORMULA
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C_n(k) = Sum_{i=1..n-1} binomial(n, i)*2^(i*(n-i))*C_i(k-1)/k.
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EXAMPLE
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1; 1,1; 1,6,1; 1,40,24,1; ...
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CROSSREFS
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Apart from scaling, same as A058843. Columns give A058872 and A000683, A058873 and A006201, A058874 and A006202, also A006218.
Sequence in context: A022169 A156601 A158116 this_sequence A156764 A156765 A015117
Adjacent sequences: A058872 A058873 A058874 this_sequence A058876 A058877 A058878
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KEYWORD
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nonn,easy,tabl
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jan 07 2001
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