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A056885 Triangle T(n,k) = number of minimal covers of an unlabeled n-set that cover k points of that set uniquely, k=0..n. 12
1, 0, 1, 0, 0, 2, 0, 0, 1, 3, 0, 0, 1, 3, 5, 0, 0, 1, 5, 8, 7, 0, 0, 1, 8, 19, 17, 11, 0, 0, 1, 12, 45, 56, 35, 15, 0, 0, 1, 17, 107, 194, 151, 65, 22, 0, 0, 1, 24, 244, 713, 728, 365, 118, 30, 0, 0, 1, 32, 547, 2697, 3996, 2413, 835, 203, 42, 0, 0, 1, 42, 1173, 10356, 24446 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
0,6
COMMENTS
Row sums give A048194.
LINKS
Sean A. Irvine, Java program (github)
EXAMPLE
[1], [0,1], [0,0,2], [0,0,1,3], [0,0,1,3,5], [0,0,1,5,8,7], ...; There are 21=1+5+8+7 minimal covers of an unlabeled 5-set.
CROSSREFS
Cf. A035347 for labeled case.
Sequence in context: A166373 A202451 A238727 * A029373 A357645 A366370
KEYWORD
nonn,tabl,nice
AUTHOR
Vladeta Jovovic, Sep 04 2000
STATUS
approved

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Last modified March 19 04:26 EDT 2024. Contains 370952 sequences. (Running on oeis4.)