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A305005
Number of labeled clutters (connected antichains) spanning some subset of {1,...,n} without singleton edges.
1
1, 1, 2, 9, 111, 6829, 7783192, 2414627236071, 56130437209370100252463
OFFSET
0,3
FORMULA
Binomial transform of A048143 if we assume A048143(1) = 0.
a(n) = A198085(n) - n + 1. - Gus Wiseman, Jun 11 2018
EXAMPLE
The a(3) = 9 clutters:
{}
{{1,2}}
{{1,3}}
{{2,3}}
{{1,2,3}}
{{1,2},{1,3}}
{{1,2},{2,3}}
{{1,3},{2,3}}
{{1,2},{1,3},{2,3}}
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 23 2018
STATUS
approved