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Search: id:A106498
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A106498 Triangle read by rows: T(n,k) = number of unlabeled bicolored graphs with isolated nodes allowed having 2n nodes and k edges, with n nodes of each color. Here n >= 0, 0 <= k <= n^2. +0
2
1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 4, 5, 5, 4, 2, 1, 1, 1, 1, 2, 4, 10, 13, 23, 26, 32, 26, 23, 13, 10, 4, 2, 1, 1, 1, 1, 2, 4, 10, 20, 39, 72, 128, 198, 280, 353, 399, 399, 353, 280, 198, 128, 72, 39, 20, 10, 4, 2, 1, 1, 1, 1, 2, 4, 10, 20, 50, 99, 227, 458, 934, 1711 (list; graph; listen)
OFFSET

0,6

COMMENT

The colors may be interchanged.

REFERENCES

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

LINKS

R. W. Robinson, Rows 0 through 7, flattened

EXAMPLE

Triangles A106498 and A123547 begin:

n = 0

k = 0 : 1, 1

Total = 1, 1

n = 1

k = 0 : 1, 0

k = 1 : 1, 1

Total = 2, 1

n = 2

k = 0 : 1, 0

k = 1 : 1, 0

k = 2 : 2, 1

k = 3 : 1, 1

k = 4 : 1, 1

Totals = 6, 3

n = 3

k = 0 : 1, 0

k = 1 : 1, 0

k = 2 : 2, 0

k = 3 : 4, 1

k = 4 : 5, 2

k = 5 : 5, 4

k = 6 : 4, 3

k = 7 : 2, 2

k = 8 : 1, 1

k = 9 : 1, 1

Totals = 26, 14

CROSSREFS

Row sums give A007139. Cf. A122081, A123547.

Adjacent sequences: A106495 A106496 A106497 this_sequence A106499 A106500 A106501

Sequence in context: A094102 A063746 A131338 this_sequence A093815 A093466 A125761

KEYWORD

nonn,tabf

AUTHOR

njas, Nov 14 2006

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Last modified October 6 16:13 EDT 2008. Contains 144667 sequences.


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