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A222317 Triangle read by rows: T(n,k) (n>=3, 1<=k<=n-2) = number of uniform realizable oriented matroids with n elements and rank n-k+1. 1
1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 11, 11, 1, 1, 1, 135, 2604, 135, 1, 1, 1, 4381 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

3,10

REFERENCES

Fukuda, Komei; Miyata, Hiroyuki; Moriyama, Sonoko. Complete Enumeration of Small Realizable Oriented Matroids. Discrete Comput. Geom. 49 (2013), no. 2, 359--381. MR3017917. (The (4) in the r=4 row of Table 2 should probably be (1).)

LINKS

Table of n, a(n) for n=3..27.

EXAMPLE

Triangle begins

1

1 1

1 1 1

1 1 1 4

1 1 1 11 11

1 1 1 135 2604 135

1 1 1 4381 unknown unknown unknown

...

CROSSREFS

Rightmost diagonal is A018242.

Different from A063851.

Sequence in context: A127707 A113196 A037291 * A063851 A124777 A203639

Adjacent sequences:  A222314 A222315 A222316 * A222318 A222319 A222320

KEYWORD

nonn,tabl,more

AUTHOR

N. J. A. Sloane, Feb 16 2013

STATUS

approved

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Last modified September 22 07:34 EDT 2020. Contains 337289 sequences. (Running on oeis4.)