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A334456 Number h of points and of blocks of nontrivial biplanes. 1
7, 11, 16, 37, 56, 79, 121 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A biplane is an incidence structure consisting of a set P of h points and a set of h blocks, each of which is a k-subset of P (block size k), such that every pair of points lies in exactly 2 blocks (see Alavi et al.).
LINKS
Seyed Hassan Alavi, Ashraf Daneshkhah, Cheryl E Praeger, Symmetries of biplanes, arXiv:2004.04535 [math.GR], 2020. See Introduction p. 1.
P. Kaski and P. R. J. Östergård. There are exactly five biplanes with k = 11, J. Combin. Des., 16(2):117-127, 2008.
CROSSREFS
Sequence in context: A129188 A022950 A364442 * A293343 A131626 A086762
KEYWORD
nonn,more
AUTHOR
Stefano Spezia, Apr 30 2020
STATUS
approved

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Last modified July 14 15:30 EDT 2024. Contains 374322 sequences. (Running on oeis4.)