A256980 Irregular triangle read by rows: row n gives number of connected graphs on n nodes with forcing number k (n>=1, k>=0).

1, 1, 1, 1, 2, 4, 8, 11, 2, 35, 68, 9, 252, 524, 75, 2, 2994, 7161, 934, 28, 68665, 171684, 20296, 432, 3, 3013075, 7849829, 840786, 12766, 115

Offset

1,5

References

C. E. Larson and N. Van Cleemput, Forcing Independence, Croatica Chemica Acta, Vol. 86, No. 4, Dec. 2013, 469-475.

Links

Table of n, a(n) for n=1..30.

Example

Triangle begins:
1
1
1 1
2 4
8 11 2
35 68 9
252 524 75 2
2994 7161 934 28
68665 171684 20296 432 3
3013075 7849829 840786 12766 115
...

Crossrefs

Sequence in context: A210108 A217131 A116636 * A014425 A372935 A028889

Adjacent sequences: A256977 A256978 A256979 * A256981 A256982 A256983

Keyword

nonn,tabf,more

Author

N. J. A. Sloane, Apr 24 2015

Status

approved