A260040 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.

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

Offset: 1

Author

N. J. A. Sloane, Jul 22 2015

Keywords

• nonn
• tabl

Comments

See Mullin (1967) for precise definition.

The sequence 1, 8, 72, 720,... in the first column has the same values as in A260039.

Examples

			Triangle begins:
1,
8,1,
72,15,1,
720,190,24,1,
...
		

Links

• R. C. Mullin, On the average activity of a spanning tree of a rooted map, J. Combin. Theory, 3 (1967), 103-121.
• R. C. Mullin, On the average activity of a spanning tree of a rooted map, J. Combin. Theory, 3 (1967), 103-121. [Annotated scanned copy]

Crossrefs

Row sums are A260041.

Formula

(k+1)*T(n,k) = A260039(n,k), n>=1, 0<=k

Conjecture: T(n,n-2) = A005563(n) = 8, 15, 24,.... for n>=2. - R. J. Mathar, Jul 22 2015

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

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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