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A260040
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Triangle read by rows giving numbers H(n,k), number of classes of twin-tree-rooted maps with n edges whose root bond contains k edges.
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2
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1, 8, 1, 72, 15, 1, 720, 190, 24, 1, 7780, 2345, 415, 35, 1, 89040, 29127, 6384, 798, 48, 1, 1064644, 367248, 93324, 15162, 1400, 63, 1, 13173216, 4708344, 1332528, 261708, 32400, 2292, 80, 1, 167522976, 61343667, 18829650, 4271652, 657198, 63690, 3555, 99, 1, 2178520080, 811147590, 265116720, 67358500, 12269312, 1506615, 117040, 5280, 120, 1
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OFFSET
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1,2
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COMMENTS
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See Mullin (1967) for precise definition.
The sequence 1, 8, 72, 720,... in the first column has the same values as in A260039.
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LINKS
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FORMULA
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(k+1)*T(n,k) = A260039(n,k), n>=1, 0<=k<n. [Mullin Eq. (7.1)]
Conjecture: T(n,n-3)= (n+1)*n*(5*n^2+7*n+6)/12 = 72, 190,.... for n>=3. - R. J. Mathar, Jul 22 2015
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EXAMPLE
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Triangle begins:
1,
8,1,
72,15,1,
720,190,24,1,
...
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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