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A008285 Triangle T(n,k) = number of labeled order relations on n nodes in which longest chain has k nodes (n >= 1, 1 <= k <= n). 4
1, 1, 2, 1, 12, 6, 1, 86, 108, 24, 1, 840, 2310, 960, 120, 1, 11642, 65700, 42960, 9000, 720, 1, 227892, 2583126, 2510760, 712320, 90720, 5040, 1, 6285806, 142259628, 199424904, 71243760, 11481120, 987840, 40320 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 60.

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

1; 1,2; 1,12,6; 1,86,108,24; ...

CROSSREFS

Cf. A055531, A055532, A000142, A055533.

Sequence in context: A049055 A276998 A222866 * A119274 A066991 A132875

Adjacent sequences:  A008282 A008283 A008284 * A008286 A008287 A008288

KEYWORD

nonn,tabl,nice

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 17 17:27 EST 2018. Contains 299296 sequences. (Running on oeis4.)