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A122085 Triangle read by rows: T(n,k) = number of unlabeled free bicolored trees with n nodes (n >= 1) and k (1 <= k <= n-1, except k=0 or 1 if n=1, k=1 if n=2) nodes of one color and n-k nodes of the other color (the colors are not interchangeable). 2
1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 4, 2, 1, 1, 3, 7, 7, 3, 1, 1, 3, 10, 14, 10, 3, 1, 1, 4, 14, 28, 28, 14, 4, 1, 1, 4, 19, 45, 65, 45, 19, 4, 1, 1, 5, 24, 73, 132, 132, 73, 24, 5, 1, 1, 5, 30, 105, 242, 316, 242, 105, 30, 5, 1, 1, 6, 37, 152, 412, 693, 693, 412, 152 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,10

REFERENCES

R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1978.

LINKS

R. W. Robinson, Rows 1 through 30, flattened

EXAMPLE

K M N gives the number N of unlabeled free bicolored trees with K nodes of one color and M nodes of the other color.

0 1 1

1 0 1

Total( 1) = 2

1 1 1

Total( 2) = 1

1 2 1

2 1 1

Total( 3) = 2

1 3 1

2 2 1

3 1 1

Total( 4) = 3

1 4 1

2 3 2

3 2 2

4 1 1

Total( 5) = 6

1 5 1

2 4 2

3 3 4

4 2 2

5 1 1

Total( 6) = 10

CROSSREFS

Row sums give A122086.

Sequence in context: A034851 A172453 A172479 * A209612 A209805 A238453

Adjacent sequences:  A122082 A122083 A122084 * A122086 A122087 A122088

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Oct 19 2006

STATUS

approved

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Last modified November 19 11:05 EST 2018. Contains 317350 sequences. (Running on oeis4.)